hydro link - Walter Scott, Jr. College of Engineering...4 hydrolink number 1/20 16 Dear Colleagues, The past few months since I assumed the office of President have been a cdeep immersion

NUMBER1/2016

DEEP IMPACT: THE FUTURE OF PHYSICAL MODELLING SEE PAGE 5

LARGE-SCALE TSUNAMI PHYSICAL SIMULATOR SEE PAGE 24

THE RØDSAND LABORATORY SEE PAGE 28

hydrolink

H Y D R A U L I C LABORATORIES S P E C I A L

IAHR 2017 World Congresswww.iahrworldcongress.orgCall for Abstracts

(see p 9)

Rapid developments in computer technology andelectronics over the last half century have changeddrastically our daily lives and provided new powerfultools to all branches of science and engineering.Hydraulic engineering practice and research havebeen no exception. For example, laptops performingseveral orders of magnitude more floating pointoperations per second than the Cray 1 supercom-puter introduced forty years ago, are used todayroutinely to run numerical models that solve a broadrange of hydraulic problems. The credibility of theresults of such models depends on the extent of theirvalidation with field or laboratory data. In most cases,the collection of field data is quite costly and timeconsuming, which makes the use of laboratory data amore attractive option for model validation. In addition, physical models in hydraulic laboratories offer the possibilityto conduct tests under controlled conditions and can provide new insightsinto basic processes that help advance the understanding of the under-lying physics. Using the tools offered by today’s technology researchersand practitioners are able to analyze complex flow problems andprocesses, which has resulted in two trends in the evolution of hydrauliclaboratories, the use of increasingly more sophisticated instrumentationand the design of inventive experimental facilities for the study of specialflow problems.

The instrumentation used in hydraulic laboratories has evolved as rapidlyas the hardware that led to the widespread use of numerical analysismodels. Advances in electronics and laser and acoustic instrumentationmake it possible to acquire rapidly and accurately high resolution data.For example, acoustic profilers can measure velocities several times persecond using bins smaller than one centimeter. Special instrumentationmakes it possible to extend velocity profiles to within a few millimetersfrom the bottom. Particle image velocimetry using digital cameras andspecial image processing algorithms allows calculating the surfacevelocity field over entire areas. In sediment deposition and erosion studiesthe use of underwater laser scanners makes it possible to record changesover large parts of the bottom by collecting millions of points per hour withsub-millimeter accuracy.

Hydrolink takes a look at the progress in data collection and processingmethods from physical model tests through a series of articles on thecapabilities and recent work of twelve hydraulic laboratories around theworld.

On the subject of velocity measurements, Sinfotek of Beijing describesthe development of a system using multiple synchronized cameras tocapture the evolution of the velocity field over large areas in physicalmodels, which is now used in several hydraulic laboratories in China.Articles contributed by HR Wallingford in the UK, Northwest HydraulicConsultants in Canada and Alden Research Laboratory in the USAdiscuss the use of advanced instrumentation in sediment deposition andscouring tests, and address the challenge of scaling issues in physicalmodels of sediment transport models. Past approaches to the scaling ofsediment transport that relied on distorted models had several limitations.

Today, the use of very fine particles of lightweightpolymers in combination with surfactants that reducesurface tension effects seems to provide a solution tothis problem.

Studies of erosion and deposition of different typesand size sediments in natural channels are discussedin articles that describe the work at the hydrauliclaboratories of Colorado State University and theUniversity of Tennessee at Knoxville in the USA.Besides advances in instrumentation, creative designsof experimental settings have made it possible tostudy in the laboratory flow processes in the ocean.For example, the University of Western Australia hasbuilt several recirculating water tunnels, referred to asthe ‘O-tubes’, with the ability to have either steady or

different types of oscillatory flow in it. The O-tubes have been used tostudy scouring and the self-burial of pipelines on the ocean floor, as wellas other problems of subsea structures.

An example of a quite unique facility is the large rotating platform at theLaboratory of Geophysical and Industrial Flows in Grenoble, France, usedto model geophysical flows, taking into account the rotation of the Earthand the presence of density stratification and variable bathymetry. Amongother experiments this platform has been used recently to study the thegeneration of internal waves by tidal currents on submarine ridges, andthe contribution of the evolution of such internal waves to the verticalmixing in the ocean.

Another very interesting new experimental facility is the Large-ScaleTsunami Physical Simulator at the Central Research Institute of ElectricPower Industry, in Japan. This facility can generate different sizeinundation tsunamis and has special instrumentation to measure thepressure distribution on vertical walls as well as the debris force on struc-tures from scaled logs and vehicles. Tsunami waves generated bylandslides have also been studied in one of the large basins of theCoastal Engineering Laboratory of the Technical University of Bari in Italy.The facilities of this laboratory are also used for a broad range of coastalstudies including the effect of waves on dispersion and the interaction ofjets and waves.

An interesting concept is that of the field laboratory in Rødsand, a non-tidal lagoon in southern Denmark. The laboratory consists of one buoystation and three instrument platforms in the lagoon used to test differenttypes of equipment and collect data for the development of numericalmodels. Data communication units on the platforms and remotelycontrolled water samplers facilitate project management and dataretrieval.

Because of space limitations, articles on three more laboratories will bepublished in the next issue of Hydrolink. They describe recent work at theWater Resources and Hydropower Research in China, CEDEX in Spainand Artelia in France.

DEVELOPMENTS IN HYDRAULIC LABORATORIESBY ANGELOS N. FINDIKAKIS

Angelos N. Findikakis

Hydrolink Editor

2 hydrolink number 1/2016

3hydrolink number 1/2016

IN THIS ISSUENUMBER 1/2016

IAHR

EDITORIAL .....................................................................................2

PRESIDENT’S ANNUAL MESSAGE .............................4

DEEP IMPACT: THE FUTURE OF PHYSICAL MODELLING ..............................................5

NORTHWEST HYDRAULIC CONSULTANTS .........................................................................8

ADVANCES IN PHYSICAL MODELING OFMOBILE BED SYSTEMS AT ALDEN DURING THE PAST 15 YEARS ..........................................................12

THE HYDRAULICS LABORATORY ATCOLORADO STATE UNIVERSITY ..............................10

HSL – A PREMIER LABORATORY FOR STATE, REGIONAL AND GLOBAL RESEARCH IN HYDRAULICS AND SEDIMENTATIONENGINEERING ........................................................................18

LEGI: FUNDAMENTAL FLUID MECHANICS FOR THE BENEFIT OF THE ENVIRONMENT AND INDUSTRY .....................................................................14

OCEAN-STRUCTURE-SEABED MODELLING IN UWA’S RECIRCULATING ‘O-TUBE’ FLUMES..................................................................21

LARGE-SCALE TSUNAMI PHYSICALSIMULATOR ..............................................................................24 A LARGE SCALE SYNCHRONOUS VELOCITY MEASURING SYSTEM BASED ON THE PTV TECHNOLOGY...........................................26

THE RØDSAND LABORATORY .....................................28

THE COASTAL ENGINEERING LABORATORY (LIC) OF THE TECHNICALUNIVERSITY OF BARI – ITALY ......................................30

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IAHRInternational Associationfor Hydro-EnvironmentEngineering and Research

IAHR Secretariat

Madrid OfficeIAHR SecretariatPaseo Bajo Virgen del Puerto 328005 Madrid SPAINtel +34 91 335 79 08fax + 34 91 335 79 35

Beijing OfficeIAHR SecretariatA-1 Fuxing Road, Haidian District100038 Beijing CHINAtel +86 10 6878 1808fax +86 10 6878 1890

[email protected]

Editor:Angelos FindikakisBechtel, [email protected]

Editor Assistant:Elsa IncioIAHR [email protected]

Hydrolink Advisory Board

Luis BalaironCEDEX –Ministry Public Works, Spain

Jean Paul ChabardEDF Research & Development, France

Yoshiaki KuriyamaThe Port and Airport Research Institute, PARI, Japan

Jaap C.J. KwadijkDeltares, The Netherlands

Ole MarkDHI, DenmarkRafaela MatosLaboratório Nacional de Engenharia Civil, Portugal

Jing PengChina Institute of Water Resources and Hydropower Research, China

Patrick SauvagetArtelia Eau & Environnement, France

James SutherlandHR Wallingford, UK

Luis Zamorano RiquelmeInstituto Nacional de Hidraulica INA, Chile

ISSN 1388-3445

Cover picture: The wave-overtopping facility of the Hydraulics Laboratory at Colorado StateUniversity


Dear Colleagues,

The past few months since I assumed the officeof President have been a deep immersion in thediversity of IAHR activities. The sterling efforts ofRoger Falconer as past President and theformer IAHR Council should be recognized assetting the foundation for many new initiativesthat will contribute to the vibrancy of theAssociation. Initiatives include the launching ofthe new Journal of Ecohydraulics (JoE) with ourpublishing partner Taylor & Francis and thecreation of a new Technical Committee on FloodRisk Management under the leadership ofProfessor Larry Weber. JoE will be formallylaunched in May 2016 at a TechnicalSymposium sponsored by the China Institute ofWater Resources and Hydropower Research(IWHR) in collaboration with IAHR. Theleadership of founding Editors Dr. ChrisKatopodis and Dr. Paul Kemp and the wing ofour Ecohydraulics Committee chaired byFrancisco Capel will ensure JoE has a strongstart with several seminal papers expected inthe opening issues.

The expansion of the Secretariat into IWHR inBeijing is proving to be a great success andSecretary General Dr. Jing Peng has recruited atalented staff and this enhanced supportstructure for our Divisions and TechnicalCommittees means that 2016 will be a recordyear for IAHR specialist events and activities. Acomplete list is on the Calendar of the IAHRwebsite and spans Hydroinformatics in Incheon(Korea) to River Flow in St Louis (USA).RiverFlow2016 will include inaugural activities ofthe Flood Risk Management TechnicalCommittee. Our regional conferences will beheld in Liège, Belgium (Europe), in Lima, Perú(Latin America) - expected to be the biggestIAHR event of 2016; in Colombo, Sri Lanka(Asia Pacific); and our recently established IAHRMENA (Middle east and North Africa)Committee is sponsoring the third ArabianCoast Conference in Dubai organized by theDubai Municipality in November.

There have been several memorable activitiesduring the past few months since I took over thehelm. On October 27th, Hohai University, one of

the elite global institutions dedicated to waterresearch and a longstanding IAHR member,celebrated its100th Anniversary. The ceremonywas attended by almost 30 000 people andcultural displays were reminiscent of theopening of the Beijing Olympics. I was privi-leged to be invited to highlight the long collabo-ration between Hohai University and IAHR. Atthe same event, Professor Xu Hui, President ofHohai University hosted a Chinese-ForeignUniversity President’s Forum onInternationalization and Innovation-OrientedTalents Cultivation. Both IAHR ExecutiveDirector, Dr. Christopher George, and I wereable to participate and explore how IAHRstrategic directions align with many majorUniversities. Congratulations Hohai Universityon a spectacular event and good luck with asecond century of success!

Professor Donatella Termini hosted the 2015Yalin Memorial Colloquium in Italy. This interna-tional meeting sponsored by the IAHR FluidMechanics Committee included a remarkableplenary lecture by Professor Vlad Nikora, Editorof our Journal of Hydraulic Research, andcreated a stimulating retreat environment forearly career researchers to engage insubstantial technical debate with some of thetop researchers in the field of sedimenttransport and turbulence. This carefully struc-tured approach proved to be an excellent wayto explore technical issues and establish inter-national collaboration for research and publica-tions. Further north in Europe, UNESCO-IHEhosted a retirement symposium for Professor

Arthur Mynett, Vice President of IAHR on 27 November. The symposium marked aremarkable career and included stimulatingtalks by Dr. Dick Yue of the MassachusettsInstitute of Technology (USA) describing theOpenCourseWare experience that has trans-formed higher education and Dr. VladanBabovic who described emerging techniquesfor managing uncertainties in Hydro-science. In February following the annual ExecutiveCommittee meeting in Madrid I held importanttalks with Tomás Sancho and Teodoro Estrela ofthe World Council of Civil Engineers with whomIAHR is closely collaborating in initiatives suchas the Journal of Water Engineering andResearch and RIBAGUA to bring scientificinnovation into practice.

These are just a brief sampling of activities thatdemonstrate these are exciting times for IAHR.On behalf of the Council and the Secretariat, Iwould like to emphasize that IAHR is yourprofessional association. We welcome andembrace your ideas to foster innovation inhydro-science and engineering and to build ourinternational network of researchers and practi-tioners. You can follow IAHR events and activ-ities throughout the year through our NewsFlashWorld eZine and by signing up to our new andimproved social media feeds.

Sincerely,

Peter GoodwinPresident

PRESIDENT’S ANNUAL MESSAGE

IAHR President PeterGoodwin addresses 30 000 people during theHohai Universitycentenary celebration



IAHR

Dr David Todd is a marinescientist at HR Wallingfordwith responsibility forrunning the Fast FlowFacility. He holds a PhD insediment transport and

has worked with the Fast Flow Facility sincebefore it opened.

Dr James Sutherland is aTechnical Director at HRWallingford with 25 years’experience of nearshorehydrodynamics, sedimenttransport (including scour

around coastal structures and coastalerosion) beach management and waveforces on maritime structures. He is ViceChair of the IAHR Coastal & MaritimeHydraulics Committee.

Dr John Harris is aTechnical Director at HRWallingford, a CharteredEngineer and a CharteredMarine Scientist withspecialist skills in

numerical hydrodynamic modelling,turbulence and sediment transport.

Professor RichardWhitehouse is a CharteredGeographer and TechnicalDirector at HR Wallingfordwith responsibility for theFast Flow Facility. His

main focus is on sediment transport andgeomorphology in river, estuarine, coastaland subsea environments.

Physical modelling has been a mainstay of HRWallingford since the laboratory was estab-lished in the 1940s. In the beginning, waveswere made in a large, outdoor basin by twomen pushing a wave paddle between twopoints and a foreman with a stopwatch blowinga whistle to maintain the correct period. As youcan imagine, tests were short in duration!

Almost 70 years later, enter the Fast FlowFacility. This new standard in physicalmodelling was developed to take physicalmodelling at HR Wallingford into the future. Anextremely versatile facility, the Fast Flow Facilityenables the production of fast currents andlarge waves in deep water, allowing physicalmodel tests to be run at larger scales thanwould otherwise have been possible – deeper,faster, bigger. The first year of operation hasseen a suite of commercial operations under-taken investigating novel scour protection, tidalturbine systems and, most recently, extensivetesting of a number of offshore wind relatedstructures for Danish Oil and Natural Gas(DONG) Energy. In addition to this, the facilityhas been home to exciting collaborativeresearch with world-leading academics andprivate, company-funded research designed tokeep HR Wallingford at the cutting edge ofscientific developments.

Physical modelling has developed greatlyduring HR Wallingford’s history, but no changehas been as great as that seen in the last 25years with the advent of personal computers,laser and acoustic instrumentation. Fifteenyears ago, scour experiments relied upon oneor more scientists moving touch-sensitive bedprofilers around a structure to make measure-ments of scour development. This methodallowed 8 radials of approximately 125 points tobe made in a 30 minute period – a total ofapproximately 1 000 points per half hour. Morerecently, HR Wallingford has made use ofterrestrial laser scanning systems in our largewave basins to allow greater, more repeatable

coverage that is less subject to human error.However, this technique requires the facility tobe free from water as reflections from watersurfaces cause errors in the measurements.This technique, therefore, while perfect fortasks like identification of breakwater armourmovement, was not suitable for the new FastFlow Facility.

The 4 m width of the Fast Flow Facility mainchannel allowed us to install a fully program-mable x-y traverser system, which movesinstruments up and down the flume to preciselyknown locations. We now deploy underwaterlaser scanners within the flume that arecapable of recording approximately five millionpoints with sub-millimetre accuracy in half anhour - five thousand times what we werecapable of just 15 years ago. The laserscanners are able to cover a large area withgood temporal resolution, providing data that iscomprehensive in its coverage, representativeof the experiment being undertaken,repeatable (as the exact position of each pointis known) and less subject to human error. Inaddition, as these laser scanners are fullysubmersible, there is no need to stop testing ordrain the facility as scans can be undertakenwhile experiments are ongoing.

Bathymetry measurements are not the onlyaspect of physical modelling that has changeddrastically in the last 25 years. Flow profilesused to be restricted to a few points in thewater column and were measured usingpropeller meters. However, with the acousticsrevolution resulting in instruments such as theNortek High Resolution Aquadopp – capable ofbins as small as 7 mm and sampling rates ofup to 8Hz – flow profiles can now be estimatedacross most of the water column (with blankingdistances immediately below the instrumentand immediately above the bed) both quicklyand accurately.The areas immediately sub-surface or abovethe bed can be sampled using the Nortek

HR Wallingford’s Fast Flow Facility, one of the world’s largest marine test facilities, was opened inOctober 2014. Now, one year on, this versatile facility is setting the pace in physical modelling.

DEEP IMPACT: THE FUTURE OF PHYSICAL MODELLINGBY DAVID TODD, JAMES SUTHERLAND, JOHN HARRIS & RICHARD WHITEHOUSE



Figure 1 - Underwater laserscanner profiling the bathymetryaround a suction bucket pile

Figure 2 - Aquadopp installed inFast Flow Facility

Figure 3 - Wave gauges, suctionbucket pile and Vectrino (on right)prior to a scour test

Figure 4 - Vectrino II ADVdeployed in the Fast Flow Facility

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Vectrino II – an acoustic instrument capable ofmeasuring the three components of velocity ina 30 mm section at 1 mm intervals down toapproximately 3 mm above the bed atsampling rates of up to 100 Hz. Such highsampling rates allow the investigation of turbu-lence and wave characteristics.

These instruments have all been utilisedsuccessfully during the first year of operation inthe flume. The most recent commercial work,undertaken for offshore wind developer DONGEnergy, has involved exploring alternatives tothe traditional monopile foundation. Well under-stood and heavily utilised in shallower near-shore regions, as offshore wind moves intodeeper water, larger monopiles are requiredwhich must be installed at greater depths.These factors are resulting in monopiles slowlybecoming less viable as foundation structures.Because of this, developers are designing andtesting alternative foundations in order toreduce costs and keep offshore wind compet-itive within the energy market place.

Even in deeper water, offshore wind farms areoften sited in areas affected by strong tidalcurrents in combination with steep, nearbreaking waves. These conditions can result inscour, posing a risk to the stability of turbinefoundations, cables and cable crossings, whileprotection and mitigation works come at a highcost. Optimisation works for scour protection

are still developing. Often, scour protectiondesigns have been tested with dominant waveconditions only due to the limitations of the testfacilities. To cover real exposure conditions forthe North and Irish seas for example, the abilityof the Fast Flow Facility to reproduce designconditions of combined waves and currentsunder true live bed conditions, with mobilesediment and at a large scale is of significantimportance for an optimised and yet robustscour protection design.

For deep water applications, a new suctionbucket jacket foundation design has beenrefined by DONG Energy as an alternative tothe traditional monopile. This new structurerequired physical model testing to determinehow the structure interacts with, and impactsupon, the local hydrodynamic conditions andthe surrounding seabed. HR Wallingford hasbeen carrying out physical model testing ofscour response to optimise the design of thesuction bucket jacket and mitigate scour devel-opment.

Key to this testing was the ability to run bothfixed and live bed conditions in the Fast FlowFacility, allowing investigations into thepotential depth of scour and the stability ofrock armour of various sizes and gradings.Gathering information on the size and extent ofprotection that is required under differinghydrodynamic

conditions is vital to the survivability of thescour protection.

An underwater laser scanner was utilised tomeasure the bathymetry before, during andafter each test, providing details of the devel-opment of scour both temporally and in extent.Current profiles, collected using the AquadoppHR profiler and Vectrino II Acoustic DopplerVelocimeter (ADVs) have provided a record ofthe hydrodynamic conditions run in the facility.Twin-wire wave probes located at differentpoints along the flume provided detailed wavespectra, while a High Definition (HD) under-water video camera was used to provide real-time visual feedback of scour developmentand armour stability.

Physical modelling techniques have changedmarkedly over the last quarter century with theadvent of new measurement capabilitiesallowing greater coverage of test areas, bothtemporally and spatially. The Fast Flow Facilitywas built to be the future of physical modellingat HR Wallingford, with its first year proving ahuge success as it utilises the latesttechnology to deliver large-scale commercialand research projects. Progress within thefacility also shows no sign of slowing, with thein-house development team set to release aset of rapid calibration wave probes and ajacking system for the wave paddle in the nextfew months. n




IAHR

As existing hydroelectric facilities age, and asnew facilities are developed, the managementof sediment both upstream and downstream ofthese developments is repeatedly identified asa critical parameter in the project life cycle. Forover 50 years specialists at Northwest HydraulicConsultants (NHC) and Lasalle|NHC havebeen utilizing in-house hydraulic laboratories,together with advanced numerical methods,analyses and field investigations, to assistclients throughout North and South Americaand elsewhere in developing techniques toeffectively manage sediment at their projects.

The Problems The management of sediment accumulationand passage at hydroelectric projects is anongoing and increasing problem around theworld. The most prominent problems

associated with sediment accumulation,passage and scour at hydroelectric facilitiesinclude loss of storage, restricted flow to theintake, damage to equipment, and degradationdownstream of the project often leading to lossof habitat.

Many of today’s large hydroelectric projectswere built with a dead storage capacitydesigned to trap sediment for a period ofapproximately 50 years. Since many of thesefacilities are now approaching their design life, itis expected that the problems associated withupstream sediment accumulation will becomemore pronounced in the coming years. Smaller,run-of-river facilities which were designed withminimal storage but are often located on steep,sediment-laden rivers are potentially subject toannual sediment volumes that must be divertedaway from the intake by some means.As a reservoir fills with sediment, water depthsare reduced and sediment transport capacitywithin the reservoir increases. This results inmore sediment reaching the intake, which canrestrict the volume of water entering the intakeduring periods of lower flows and can increaseabrasion damage to the turbines and othermechanical equipment. The resulting impactson performance, operation and maintenancecan have a huge impact on the economic andtechnical viability of the project. In 2009 it wasestimated that the total yearly loss resulting fromsediment accumulation in reservoirs wasreaching almost US$20 billion (ICOLD 2009),and this number is expected to continue toincrease as the world’s reservoirs continue to fillwith sediment.

The ToolsNumerous examples are cited in the literaturewhere reservoirs have filled with sediment well inadvance of time predictions made during theproject design, requiring development ofremedial sediment management measures atexisting facilities. Similarly, new projects arebeing developed each year that must considersediment management measures in their

NORTHWEST HYDRAULIC CONSULTANTS – USING EXPERIMENTAL METHODS TO ADVANCE SEDIMENT MANAGEMENT SOLUTIONS AT HYDROELECTRIC FACILITIESBY BRIAN R. HUGHES

designs. Tools available to analyze and developsediment management measures includedrawing on the experience of sedimentationspecialists, implementing field investigationsand monitoring systems, applying advancednumerical analyses, and conducting reduced-scale experiments in a hydraulic laboratory. Inmany cases, two or more of these tools arerequired to arrive at a technically feasiblesolution.

NHC and Lasalle|NHC have operated hydrauliclaboratories in Canada and the United States forover 50 years. While the laboratories haveformed the foundation for many studies relatedto sediment management at hydroelectric facil-ities, the capabilities and expertise of the firms’senior specialists, together with advancementsin numerical analyses and field investigations,have all played important roles in the devel-opment of practical and effective solutions formanaging sediment at these facilities. Reservoir sedimentation and scouringprocesses, where 3D effects are important,

Brian Hughes holds a Bachelor's degree inCivil Engineering and a Master’s degree inWater Resources, both from the Universityof British Columbia. He has over 25 years ofexperience in modelling and hydraulicdesign having worked on a variety ofhydroelectric developments, spillwayprojects and sediment transportinvestigations. Since joining NorthwestHydraulic Consultants in 1988, Brian hasparticipated in over 200 physical andnumerical model studies. He is a Principal ofNHC and the Director of the firm’s physicalmodelling operations.

Figure 1 - Sediment accumulation within a hydro-electric reservoir in the Western United States



usually require the use of a physical (scale)model. The biggest challenge in conductingreduced-scale experiments to addresssediment management issues is the scaleeffect associated with simulating the scour anddeposition processes occurring in the field.Nonetheless, NHC and LaSalle|NHC haveadopted experimental methods using finesands, low-density model sediments anddistorted scale models to study a range ofsediment-related problems commonly found athydroelectric projects. The experiments conducted at NHC ofteninclude both a “comprehensive model” and alarger-scale “section model”. The compre-hensive model represents a relatively large areaof the reservoir and downstream channel, andis used to assess the general sedimentationpatterns and behavior of both suspended andbedload sediments approaching the project.Typical scales for comprehensive models of thistype generally fall between 1:40 and 1:100. Thesection model of the intake structure ordesanding facility is then used to provide adetailed evaluation of their performance andrefine their designs to make them more efficient

at preventing sediment from entering thepenstock. Examples of comprehensive andsection models are illustrated in Figures 2 and 3.In addition to laboratory experiments, NHC oftenapply advanced numerical methods and fieldinvestigations to gain a better understanding ofthe processes that are occurring in the field.These methods are applied both during thedesign stage for assessing the performance ofnew facilities and during the operation stage ifsediment management problems havedeveloped since the facility was constructed.The results of the numerical analyses and fieldinvestigations are often used as input param-eters for a physical model used to confirm theirfindings.Numerical methods utilized by NHC include 1-,2- and 3-dimensional models, with both hydro-dynamic and morphologic capabilities. Recentstudies conducted by NHC include assessingthe morphologic impacts downstream of aproposed hydroelectric development in westernCanada using Telemac 2D (Figure 4), andassessing the efficiency of a proposed sedimentbypass tunnel at an existing hydroelectric devel-opment in the United States (Figure 5). Field


monitoring studies have included the installationof turbidity meters and bed level sensorsupstream of the intake for a run-of-river project,to provide real-time information critical to power-house operation.Finally, in-house specialists in sedimentationand geomorphology use the informationgenerated from these tools to develop solutionsdesigned to mitigate the problems associatedwith sediment accumulation.

The SolutionsHaving developed the necessary tools, NHChas worked with clients on establishingsolutions for both existing and proposed hydro-electric facilities, ranging in capacity from lessthan 1 MW to over 2000 MW. The solutions havebeen as varied as the problems themselves. Forsmall, run-of-river developments they caninclude (i) field monitoring to guide operation,(ii) controlling the sediment source, (iii) incorpo-rating sediment guide walls or sediment vanesupstream of the intake, and (iv) periodicdredging or sluicing of the accumulatedsediment. For larger developments the solutionscan also include incorporating sediment bypass

Figure 4 - Prediction of morphologic changes downstream of a proposedhydroelectric project in Canada using Telemac2D

Figure 5 - CFD particle tracking used to assess the efficiency of a proposedsediment bypass tunnel at an existing hydroelectric project

Figure 2 - Comprehensive mobile-bed model using low-density modelsediments

Figure 3 - Detailed section model of a desanding facility for a project in India



IAHR

and/or desanding facilities. In many cases thepreferred solution may include two or more ofthese components.

Examples of these solutions include a small run-of-river development in Western Canada whereturbidity meters and bed level sensors wereinstalled upstream of the power tunnel intake.Information from these sensors is used by theoperators to assess when the power intakeshould be shut down to protect the turbines andwhen the sluicing facilities should be operatedto remove accumulated sediment from theheadpond. For a much larger project, fieldmonitoring sensors, sediment sluicing facilitiesand a desanding facility were all incorporatedinto the design to manage very high sedimentloads at the intake. In this case, NHCconducted extensive field investigations,numerical model analyses and mobile-bedphysical model studies to arrive at a practicaland effective solution.

The Next StepsAs existing hydro projects continue to age andas new projects are developed, the need toeffectively manage sediment at these facilitieswill continue to increase. At the same time, theexperience of specialists and the capabilities ofinvestigative tools will continue to improve, and

the solutions will continue to evolve. NHC andLaSalle|NHC will continue to advance theircapabilities and expand their “toolbox” to assistclients with developing solutions related tosediment management – whether a 0.5 MWdevelopment on a small stream or a 2000 MWdevelopment on one of the world’s largestrivers. Advances in numerical analyses and inthe capabilities of real-time field sensors may

reduce reliance on large-scale physical models;however, specialised skills and experimentalcapabilities for site-specific investigations andthe development of innovative solutions willcontinue to be in demand for several decadesto come. n

ReferencesInternational Committee on Large Dams, Sedimentation Committee.

March 2009. Sedimentation and Sustainable Use of Reservoirsand River Systems, Draft ICOLD Bulletin

Figure 6 - Intake facility that includes field monitoring sensors, sediment sluicing facilities and a desander




To help predict the effect of channel modifica-tions on sediment transport and deposition,engineers have long used scaled physicalmodels. If used properly, modeling can providevery helpful information for resolving sedimentproblems at riverine water intakes. During thepast 15 years, there have been significantadvances in physical modeling of sedimenttransport at Alden, further reducing the risk ofbuilding expensive solutions that may not work.This article considers advances in four areas:low density materials available for modelingsediment, instrumentation available for physicalmodels, computer models that are coupled withphysical models, and field data collection.

Scaling and Sediment SelectionIn a physical model, the particle size scales withthe model length scale; in a 1:100 scale model,the sediment should be 100 times smaller thanin the prototype. This presents challenges whenmodeling sand bed rivers where the modelsediment must have a diameter on the order ofmicrons. When impractically small modelsediment is required, based on scaling criteria,coarser sediment can be used, but with a lowersediment density.

Historically, mobile bed models at Alden andelsewhere were constructed with coal beds.Coal has a specific gravity of about 1.4 wheresand has a specific gravity of about 2.65.However, coal particles tended to be coarser

Alternative Model SedimentA wide range of approximately sphericallyshaped particles with specific gravities as low as1.05 and particle sizes as small as 60 to 100microns have become available in the past 10 to15 years. Polymers and other materials can bemade to a specific density. Through grinding, it ispossible to obtain a defined grain size distri-bution. Physical models can now be constructedwith less or no tilting and distortion, reducingscaling problems. The use of lightweightsediment can introduce operational challengeswith surface tension and getting the sediment tosink; however, these are readily addressed withsurfactants that reduce surface tension withoutchanging other properties of the water.Lightweight sediments should be used whenappropriate to minimize scale effects from modeldistortion. Figure 1 shows a sediment bed beinginstalled on an underlying fixed bed model.

InstrumentationOne of the most significant advances in modelinstrumentation has been with the use of laserscanners such as the one on the yellow tripod inFigure 2. Historically, after a model test, the staticwater level in the model was slowly lowered toestablish contour lines at the water/bed interface.The contour lines were surveyed and a contourmap of the beginning and ending riverbed condi-tions were produced. The laser scanners now inuse at Alden can automatically measure thehorizontal and vertical position of millions of

ADVANCES IN PHYSICAL MODELINGOF MOBILE BED SYSTEMS AT ALDENDURING THE PAST 15 YEARSBY DANIEL GESSLER

Figure 1 - Lightweight sediment being installed in a physical model Figure 2 - Sub-millimeter scanner in use on a model to determine scour anddeposition. Scanner is on the yellow tripod and the river bed is blue

than sand and resulted in physical modelsdominated by bed load. Further, these modelsfrequently required tilting (enhanced slope ordistorted) to obtain any sediment transport atall. Tilted models have significant scalingproblems. Einstein (1967) and Gessler (1971)both demonstrated the following limitations todistorted models:1. Distorted models can only be designed forone discharge

2. The hydraulic time scale differs from thesediment time scale, by a large amount(factor of 10 or more) for only a small (2:1)distortion

3. The suspended concentration in the modeldiffers significantly from the prototype,compromising model results

4. Local scour and deposition cannot bemodeled, because the angle of repose in themodel does not have the distortion of themodel

Einstein and Chien (1956), Einstein (1967) andGessler (1971) indicate that distorted modelsare a compromise which should be avoidedwhen possible. The cost of a distorted modelcan be significantly less than that of an undis-torted model and testing schedules can alsobe shorter. As such they have become popularwith some engineers. However, results arepurely qualitative and in some instances haveresulted in the construction of sedimentationcounter measures that exacerbated (ratherthan mitigated) sedimentation problems.




termining three dimensional flow patterns andeddies. Three dimensional numerical tools arenow used to compliment physical modeling ef-forts. While three dimensional models have sig-nificant limitations for predicting changes in bedelevation associated with sediment scour ordeposition, the models are extremely valuablefor visualizing flow patterns that may be difficultto measure directly in a physical model. The ad-ditional cost of a parallel numerical modeling ef-fort is typically offset in a savings in the physicalmodel and additional insight that is gained aboutthe physical model. Every proposed physicalmodel study at Alden now considers the poten-tial benefits of a parallel numerical modelingstudy. Figure 3 shows CFD results that are su-perimposed on the physical model in a hybridCFD – physical model study.

Field DataThe fourth pillar of physical modeling is fielddata. The most significant advances in field datacollection have been the ability to measure watervelocity and bathymetry. Historically, point veloc-ity measurements were made to determine thetime averaged velocity at a single point. Measur-ing water velocity at a range of depths and loca-tions in a large river was time consuming andfrequently cost prohibitive. The development ofAcoustic Doppler Current Profilers (ADCP) hasrevolutionized velocity measurement. Widelyused now for over 20 years, the method meas-ures the instantaneous water velocity from amoving boat and is able to acquire both the hori-zontal and vertical velocity profile across thewidth of the river. ADCP velocity data has signifi-

cant spatial fluctuations and multiple passescombined with statistical methods must be usedto analyze the data.

Bathymetric data vastly improved with the use ofDifferential Global Positioning Systems (DGPS)during the past 15 years. When combined withecho sounders and shipboard navigation sys-tems, thousands of linear feet of bathymetricdata can now be collected and processed in asingle day with a previously unachievable preci-sion. Figure 4 shows a pontoon boat equippedwith modern bathymetric survey and ADCP ve-locity measurement equipment.

SummaryTechnology has revolutionized physical modelingof mobile bed rivers in the past 15 years. Majorimprovements have been realized in the materi-als used for simulating the river sediment andlaser scanners used for measuring a model riverbed to an accuracy of 1mm or better. Combiningphysical models with three dimensional numeri-cal models can help visualize the flow patternsresponsible for the depositional patterns noted inphysical models. Field velocity measurementswere revolutionized by ADCP systems andDGPS-based surveying systems have improvedthe bathymetry used in models. n

Referencesa. Einstein, H.A. , Chien, N., (1956) Similarity of Distorted River

Models with Movable Beds, Transactions of the ASCE, Vol 121, No1, January 1956

b. Einstein, H.A., (1967) Discussion on Movable Bed Model for RiverStructure Design, Journal of the Waterways and Harbors Division,ASCE, Vol 93, February 1967

c. Gessler, J. (1971), Chapter 21, Modeling of Fluvial Processes,River Mechanics, Volume II, H.W. Shen, Editor, Library ofCongress, 70-168730

points on the riverbed, creating a point cloud thatdefines model surface. The scanners have sub-millimeter accuracy (e.g. the Trimble FX 3Dscanner) and are now used in conjunction withdata processing software to define changes inriver bed elevation to less than 1 mm modelscale. The scanner can automatically scan all ofthe surrounding environment to a distance of 50meters or more depending on the scanner.

Numerical ModelsOne of the least intuitive but equally significantadvances in physical modeling is numericalmodeling. One limitation of physical models hasbeen the time consuming effort of accurately de-

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Figure 3 - Computational Fluid Dynamics (CFD) model results superimposedon a physical model for a combined CFD – physical model study

Figure 4 - One of Alden’s boats for field measurement equipped with DGPSnavigation, bathymetry and velocity measurement equipment

Dr. Gessler is a registered professional engineer and has over 25 years of experiencein numerical and physical modeling and generally oversees the numerical and physi-cal hydraulic modeling activities at Alden. He is responsible for hydraulic modeling using computational fluid dynamic (CFD)models and one and two dimensional hydraulic models, including sediment transport models. In addition to working onnumerical models, he provides technical expertise on physical models involving sedi-ment transport. Dr. Gessler also managesAlden’s Colorado office, and strives to provide engineering recommendations andvaluable engineering options for the projectsin which Alden is involved. He is a Vice President and prior to joining Alden, heworked as a Research Scientist and AssistantProfessor at Colorado State University.

About AldenAlden (Alden Research Laboratory, Inc.) was founded in 1894, and is an acclaimed leader in solving flow-related engineering and environmental problems. The firm has 95 employees and over 150 000 sq feet ofindoor lab space on a 32 acre campus in Holden, MA, and an additional 25 000 square feet of laboratoryspace in Redmond, WA. Alden provides engineering, physical and computational flow modeling along withenvironmental and flow meter calibration services. For more information, please visit www.aldenlab.com



Robert Ettema is a Professor at ColoradoState University in Fort Collins, Colorado.Prior to joining CSU in 2015, he served asthe Dean of the University of Wyoming’sCollege of Engineering and Applied Science.Earlier, he had been a faculty member of theUniversity of Iowa’s Iowa Institute ofHydraulic Research. He attained the PhDDegree in 1980 from the University ofAuckland, New Zealand. His interestsinclude multiple facets of engineeringhydraulics including hydraulic structures,fundamental and applied aspects of alluvial-channel behavior, cold-regions hydraulics,and hydraulic engineering history. He is an IAHR Council Member.

Steven Abt is an Emeritus Professor of Civiland Environmental Engineering at ColoradoState University. He graduated as a civilengineer from Colorado State University in1973, and subsequently a PhD. Degree in1980 from the same institution withspecialization in river mechanics. Heworked as a Professor, Director of theHydraulics Laboratory, Director of theEngineering Research Center and ResearchAssociate Dean of the College ofEngineering at Colorado State University.He has over 35 years of experienceperforming scaled physical model studies,revetment testing and evaluation, sedimenttransport processes in gravel-bed riversand hydraulic structure-near prototypeexperimentation. He has publishedextensively in the field.


An illustrious history along with the availability ofextensive facilities, a capacity to deliverremarkably large water discharges, and anarray of instrumentation, make Colorado StateUniversity’s (CSU) Hydraulics Laboratory anational and international resource for tacklingfundamental and applied aspects of waterengineering. The lab’s earliest activities dateback to the 1880s work of the pioneeringhydraulics engineer of the American West,Elwood Mead (for whom Lake Mead on theColorado River is named). Its current activitiesaddress a wide range of contemporary as wellas enduring research topics, and link closely tothe university’s extensive programs of graduateeducation in water engineering, science andmanagement. As with all vibrant laboratories,the hydraulics laboratory at CSU continuouslydevelops its facilities and instrumentation inresponse to evolving research needs andopportunities.

BackgroundThe history and potential of CSU’s hydraulicslab quickly drew the attention of notedhydraulician Hunter Rouse, who in 1940 begana lengthy connection with the lab. Though his

name is primarily associated with the Universityof Iowa’s hydraulic lab, Rouse spent consid-erable time at CSU and produced a handybook (Rouse 1980) describing the historic influ-ences and people that led to the lab’s promi-nence. In his customary concise, matter-of-factmanner Rouse documents some of Mead’scontributions, along with those by many otherwell-known engineers who contributed to thelabs growth in productivity and stature; e.g.,Ralph Parshall, Emory lane, Maurice Albertson,Daryl Simons, Ev Richardson and Hsieh-WenShen; to name just a few people. Subsequentarticles, including those by Bhowmik et al.(2008), Simons (2004), and Julien and Meroney(2003), recount the work of other notableengineers whose principle contributions tohydraulic engineering were made while at thelab. The lab’s facilities also drew the interest oftalented scientists, such as the acclaimedgeomorphologist Stanley Schumm.

SettingThe physical and educational aspects of thelab’s setting give it strategic advantages sharedby few other hydraulics laboratories. Since 1962the lab has occupied a major part of CSU’s

THE HYDRAULICS LABORATORY AT COLORADO STATE UNIVERSITYBY ROBERT ETTEMA & STEVEN R. ABT

Figure 1 - An aerial view of CSU’s Hydraulics Laboratory at Horsetooth Reservoir

Hydraulics Laboratory



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bility to construct large-scale, near-prototypesize, project-specific facilities. Additionally, thelab has a well-equipped machine andinstrument shop to support the facilities andbuild experiment set-ups and instrumentation.These attributes enhance the lab’s ongoingcapacity to undertake a wide range of funda-mental as well as applied research projects.The lab’s permanent features include a compre-hensive system of fourteen pumps connectedto a network of sumps (volume of 1,223 m3).Individual pumps range in capacity from about1.5 m3/s at a head of 6 m, to about 0.017 m3/sat a head of 15 m. Portable pumps of variouscapacities are used for experiments involvingflow recirculation. The pumps connect to a fleetof flumes, although some flumes are fitted withtheir own pumps for flow and sediment recircu-lation. The fleet includes a versatile flume 8 mby 33 m in plan area, and 1.3 m deep. Figure 2shows its use in a current study involvingbraided channels (Ettema et al. 2015). A largerecirculating flume, 2.4 m by 60 m by 1.3 mdeep, is capable of recirculating water at adischarge of 2.8 m3/s and gravel-size sediment.This latter flume is fitted with a wave-maker inorder to conduct various studies on thecombined effects of wave and current action.The main lab building houses four other tiltingflumes and has ample room for temporaryexperimental installations and hydraulic models.A 40.7-hectare outdoor area adjoins the mainlab facilitating large-scale model and full-scaleprototype experiments. Additionally a further labbuilding exists for testing hydro-machineryequipment (its 1m-thick concrete floor avertsflexural vibration) and is at times used to househydraulic models and large-scale experiments.A large flume and a wave-overtopping basin are

presently in frequent use. The flume, 18 m by 6 m by 2.4 m, includes a 3.3 m-deep recessedsection. Since 2010 CSU has operated thelargest wave overtopping test facility in theworld (Figure 3). This facility, its need promptedby the damage wrought on New Orleans byHurricane Katrina, is operated using a computersystem that simulates waves larger than 2 m inheight waves. The waves spill water down over12 m-long, 2 m-wide “trays” that simulate leveesmade of soils specific to any region (Thornton etal. 2014). Various types of grass are grown insoil trays placed in a large greenhousepurpose-built for the over-topping facility. Acompanion over-topping facility consisting of aconcrete head box, chute and tailbox is used forstudying the erosion of soils and erosioncountermeasures located on steep slopes.

Concluding RemarkBy virtue of its physical and educationalsettings, and the talents of the many peopleassociated with it, CSU’s Hydraulics Laboratoryis well-positioned to continue as a national andinternational resource for water engineering andrelated sciences. n

ReferencesBhowmik, N., Richardson, E.V. and Julien, P.J., (2008). “Daryl B.

Simons – Hydraulic Engineer Researcher and Educator.” Journalof Hydraulic Engineering, 134(3), 287-294.

Ettema, R., Thornton, C. and Abt, S. (2015), “Hydraulic Modeling ofChannel-Control Structures in Self-forming Braided Channels.”36th Congress, International Association for Hydro-EnvironmentEngineering and Research, The Hague, Netherlands.

Julien, P. Y. and Meroney, R. N., (2003). “History of Hydraulics andFluid Mechanics at Colorado State University.” Proc. HydrologyDays 2003, Colorado State University, Fort Collins, CO, USA.

Rouse, H. (Ed.), (1980). Hydraulics, Fluid Mechanics and Hydrologyat Colorado State University. A book published by Colorado StateUniversity, Fort Collins, CO, USA.

Simons, D. B., (2004). “The Influence of Whit Borland and MauriceAlbertson on My Research Related to Regime Theory Applied toUniform Conveyance Channels.” Proc. Hydrology Days 2004,Colorado State University, Fort Collins, CO, USA.

Thornton, C.I., Hughes, S.A, and Beasley, J.S., (2014). “Full-scaleWave Overtopping Resiliency Tests of Grass Established onSandy Soils.” Proc. 3rd Europe Congress, IAHR, Porto, Portugal.

Engineering Research Center (ERC), locatedbelow Soldier Canyon Dam of HorsetoothReservoir in Fort Collins. Figure 1, an aerial viewof the ERC, indicates the lab’s physical setting.This setting is ideal for a hydraulics laboratoryas it provides a large water discharge capacity(up to 5 m3/s) at a very large head (107 m).Moreover, the reasonable centrality of FortCollins within the USA, and its closeness toDenver International Airport, make the labreadily accessible.The lab serves faculty and students involved inCSU’s broad, water-related graduate programs(see, for example, http://www.engr.colostate.edu/ce/degreeinfo.shtml). The programsconnect contemporary technologies in water-related areas of civil and mechanicalengineering and the geosciences. They includehydraulic and hydrologic systems and infra-structure, fluvial engineering, fluid mechanics,environmental and ecological hydraulics,coastal hydraulics, and groundwater, and arewell-known for interdisciplinary studies involvingwater-resources planning and management.The programs emphasize the application ofadvanced laboratory and field instrumentationand methods, computer technologies andnumerical modeling to practical waterengineering as well as to the enlightenedmanagement of environmental and ecologicalsystems. Today these programs have nearly200 graduate students. Over the years theprograms have led innumerable graduates tocareers in water engineering.

FacilitiesThe large space and water discharge availableto the lab enable it to operate substantialpermanent physical facilities and have the flexi-

Figure 2 - The 8 m by 33 m flume used to model a system of grade-building structures placed in a mobile-bed model of a braided alluvial channel

Figure 3 - Wave-overtopping of a grassed, soilslope placed in the wave-overtopping facility




Research with Depth and BreadthThe research conducted at HSL has threedistinct but interconnected main thematic areas,namely:1. Coarse-grained stream hydraulics, streamrestoration, sediment transport processes

2. Cohesive soil/ sediment transport dynamicsand source tracing

3. Ecological and biogeochemical processes inwatershed and estuarine environments.

Hydraulics and Sediment TransportProcesses in Coarse-grainedChannelsThe main thrust of the research activity at HSLis focused on the study of fundamental environ-mental fluid mechanics, hydraulics andsediment transport mechanics in coarse-grained streams. The improved fundamentalknowledge gained from HSL research isoriented to the solution by a suite of practicalengineering problems, thus assisting practicingengineers and other stakeholders effectivelymanage the environment in coarse-grainedstreams (Fig. 1). The spearhead of the researchin this theme is focused on developingeducated mountain stream restorationpractices, with most prominent the under-standing of the role of large boulders andsimilar structures (Fig. 2) in modifying the near-bed turbulent flows and controlling sedimenttransport patterns with implications to fishhabitat, water quality and sedimentmanagement. Furthermore, our research in this

HSL – A PREMIER LABORATORY FOR STATE, REGIONAL AND GLOBAL RESEARCH IN HYDRAULICS AND SEDIMENTATION ENGINEERINGBY THANOS PAPANICOLAOU, ACHILLEAS TSAKIRIS, CHRISTOPHER WILSON & BENJAMIN ABBAN

The recently established Hydraulics and Sedimentation Laboratory (HSL) at the University ofTennessee at Knoxville (hsl.engr.utk.edu) constitutes a premier facility for conducting innovativefundamental and applied research in environmental fluid mechanics, sedimentation engineeringand watershed science. With state-of-the-art facilities and equipment, HSL aims to provideknowledge and address hydraulic engineering problems, while promoting at the same time theadoption of adaptive strategies towards addressing contemporary and future challenges at thestate, regional, national and international levels.

Figure 1 - (a) boulder in mountain stream; (b) simulation of a boulder in HSL and resolution of itssurrounding turbulent flow field using Hi-Speed Particle Image Velocimetry (PIV)

a

b




theme goes hand-in-hand with the worldwidetransition in analyzing bedload transport froman Eulerian to a Lagrangian perspective. Workin HSL concentrates on investigating coarsebed granular dynamics and grain-to-grain inter-actions, as well as diffusion processes. Alongthe same lines, research at HSL also focuseson scour around stream restoration and otherhydraulic structures placed in coarse-grainedstreams, a topic which has received minimalattention in the past. For undertaking thisresearch, HSL has two 10-m long, 0.60 m wide,water-recirculating flumes with adjustable slopeup to 5%, one of which also allows sedimentrecirculation (Fig. 3). A plethora of measuringequipment is available for making high qualityflow and sediment transport rate measure-ments, including a state-of-the-art Hi-SpeedParticle Image Velocimetry (PIV) system, a 2D Laser Doppler Velocimeter (LDV) system,several 3D Acoustic Doppler Velocimeters(ADV), geophones, micro-pressure trans-ducers, Radio Frequency IDentification (RFID)sediment particle tracking equipment and,sonar bathymetric devices among others. TheHSL also offers space, electromechanical infra-structure and unique expertise for constructingphysical models.

Cohesive Sediment Transport andDynamicsA key topic of HSL research is the erosion ofcohesive stream banks (Fig. 2), a process

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Thanos Papanicolaou,Professor and HenryGoodrich Chair of Excellence in Civil andEnvironmental Engineer-ing at the University of

Tennessee, Knoxville is the Director of theHydraulics and Sedimentation Laboratory.Since receiving his M.Sc. and Ph.D. degreesin Civil and Environmental Engineering fromVirginia Tech, he has been actively involvedin experimental fundamental and appliedresearch in environmental fluid and sedimenttransport mechanics, as well as in numericalmodeling of riverine and watershed transportprocesses. Having authored over 100 articlesin 42 different discipline journals, he is currently the Director of the Tennessee WaterResources Center, as well as the chief Editorof the Journal of Hydraulic Engineering,ASCE.

Achilleas Tsakiris wasappointed as the managerof the Hydraulics and Sed-imentation Laboratoryafter completing his M.Sc.and Ph.D. studies at the

University of Iowa in 2014. His researchinterests include fundamental hydraulics andinteraction between sediment, structures andflow turbulence, modeling as well as fluidiza-tion of cohesive sediment. He is alsoactively involved in sensor development forsurrogate bedload transport and bridge pierscour. .monitoring.

Christopher Wilson is thefield coordinator for HSL.He holds a B.S. in Biol-ogy/Ecology from RhodesCollege and a Ph.D. inGeological Sciences.

Additionally, he has worked at the USDA-ARSNational Sedimentation Lab before joiningthe team. His research interests includeexamining the movement of water, soil, andcarbon through the Earth’s critical zonethrough source tracking of radionuclides and other hydropedological properties, as well as studies related to bank erosion, soil health,and evaluating conservation practices.

Benjamin Abban is aresearcher at HSL. He holds an M.Sc degreein Civil Engineering fromthe University of CapeTown. His research inter-

ests include upland erosion processes,watershed dynamics and scaling laws, knick-point development and migration, and localscour around bridge piers and abutments.He is also interested in computational model-ing of river networks, as well as the use ofvarious sensor technologies such as RadioFrequency IDs and laser scanning systemsfor monitoring land surfaces changes andsediment fluxes.

Figure 2 - Placement of hydraulic structures (barbs and spurs) for protecting river banks from erosion and preventing loss of agricultural land




encountered world wide with important implica-tions on lateral stream migration, safety ofbridge, highway and other infrastructure, waterquality and loss of arable land. Research atHSL concentrates on isolating the differentmechanisms of bank erosion and quantifyingthe erosional strength of different soils, as wellas the effects of soil properties, temperaturechanges and vegetation. In doing so, we seekto develop predictive relationships for bankerosional strength suitable for use by practicingengineers and planners. Instrumental to thestudy of cohesive bank erosion at HSL are aprototype conduit (Fig. 3) and a mini-openchannel mobile flume which has beendesigned in-house specifically for estimatingthe critical erosional strength of bank materialsin the laboratory or in situ. Within the frameworkof cohesive sediment transport, work at HSLalso focuses on the phenomenon of fluidizationand the resulting piping within soils that arisesfrom pore water pressure variations in the soil.Fluidization is applications in fluid mudmanagement in harbors, estuarine dynamics,dam seepage and gas (methane or gashydrates) upwelling in lakes and dam reser-voirs. HSL offers the capability and technicalexpertise for replicating the fluidization andpiping phenomena in the controlled laboratoryenvironment thus allowing isolation of theunderlying physical mechanisms. A wide arrayof measurement equipment, such as miniaturepressure transducers, high-definition imagingand image analysis and a microscope lensassist in making detailed measurements ofpore water pressure and observations of thesoil structure.

Source Tracing and Nutrient CyclingResearch at HSL is also focused on under-standing the source and transport of sedimentand nutrients (e.g., nitrogen and phosphorus)

research on Critical Zone dynamics forstudying sustainable ways of producing food,water and energy. Along the same lines, HSLplays a key role worldwide in developing newgeneration of sensing technologies for devel-oping “smart” infrastructure and for supplyingnewly developed numerical models withaccurate and actual data. A key step in thisdirection is the development of an automated,remotely operating system based on RFIDtechnology for automated monitoring of scouraround bridge piers and other hydraulic struc-tures. In these new initiatives, HSL is partnering andcollaborating with many institutions in the public and private sectors nationally and internationally. HSL is building connections withother laboratories in Australia, New Zealand,India and Europe, with the United StatesBureau of Reclamation (USBR) and the UnitedStates Department of Agriculture – AgriculturalResearch Service (USDA-ARS) laboratories,and with the United States Army Corps ofEngineers (USACE) and the United StatesGeological Survey (USGS) southeastern region to address significant environmentalproblems such as the hypoxia and the BP Horizon disaster problems in the Gulf ofMexico. In addition HSL is developing apartnership with the Tennessee Valley Authorityon water and dam operations as well as withORNL on biogeochemical cycles andhydropower energy. n

Figure 4 - Rainfall simulator unit deployed in situ for studying upland erosionin an agricultural field

Figure 3 - Perspective view of HSL with the 2 experimental flumes (left and topright) and the conduit erosion flume (bottom right)

Research at HSL focused on understanding the source and transport of sediment and nutrients in intensivelymanaged landscapes

in urban and agricultural watersheds andparticularly in intensively managed landscapes.Through this understanding, we sought toinform the decisions of land managers, farmersand other land stakeholders towards a moresustainable agriculture. For this type ofresearch, HSL has a mobile rainfall simulatorunit capable of performing in-situ experiments(Fig. 4) simulating natural storms for studyingthe movement of soil at the plot or watershedscales. The mobile unit is complemented withan array of equipment for measuringsuspended sediment concentration, infiltration,bed microtopography, moisture, erosiondepths, pressure and temperature. Furthermore, HSL is equipped with a gammasourcing facility that allows tracing sedimentwith radioisotopes including 210Pb, 7Be, and137Cs. Under the lead of Prof. Papanicolaou,Dr. C.G. Wilson coordinates the field experi-mental campaigns and the radionuclidetracing, which are complemented withnumerical modeling supervised by B. Abban.This research is enhanced with the study ofcarbon cycling in the landscapes for gaininginsight into the fertility of soil.

New Initiatives and Worldwide NetworkingConstantly adjusting and adapting to contem-porary challenges, HSL seeks to expand itsresearch capabilities in parallel with the threemain research thematic areas. As part of thiseffort, HSL is applying knowledge gained by



Nominations open online until 31 December 2017

www.psipw.org e-mail: [email protected]

R e c o g n i z i n g I n n o v a t i o n

Invitation for Nominations

Various devices can be employed to produceturbulence, such as towed grids and topog-raphy models to reproduce boundary layers andwakes of the natural environment. Thermalconvection can be sustained by heating with upto 20 kW.

Particle Imaging Velocimetry (PIV) systemsprovide time resolved velocity fields in bothhorizontal and vertical planes of up to 3 m × 4m in size, with a relative precision of 2%. Thelaser sheet can scan a volume, providing three-dimensional three-component velocity fields, aquite unique feature for such large-scale


The Coriolis platformThe Coriolis platform (Fig. 1), 15 m in diameter,is the largest rotating platform in the worlddedicated to fluid dynamics. Its main activity isthe experimental modeling of geophysical flows,taking into account the rotation of the Earth, inthe presence of density stratification or topog-raphy. The large size provides an approach tothe inertial regimes that characterize oceandynamics, with little influence of viscosity andcentrifugal force. Laboratory experiments canthus provide support to model ocean dynamicsand interpret observed fluid process undersimplified and well-controlled conditions.

The platform has been rebuilt in 2014 on themodel of the old platform built in 1960, withmany improvements. The total weight of theplatform is 150 tons and it supports an extraload of 150 tons of water, corresponding towater height of 1.1 m in the cylindrical tank, 13 m in diameter. Its rotation period can be setwith high stability between 10 and 1 000 s. Thetank can be filled with homogeneous or densitystratified water. Stratification is made by fillingthe tank with a computer-controlled mixture fromtwo ancillary tanks (90 m3 each) with specifiedsalinity and temperature. Model sedimentsmade of plastic particles can also be used.

LEGI: FUNDAMENTAL FLUID MECHANICS FOR THE BENEFIT OFTHE ENVIRONMENT AND INDUSTRYBY JOËL SOMMERIA, THIERRY MAITRE & JEAN-PIERRE FRANC

The Laboratory of Geophysical and Industrial Flows (LEGI) (www.legi.grenoble-inp.fr) in Grenoble,with over 100 employees, conducts leading-edge research in the field of fluid mechanics. Bothenvironmental and industrial flows are investigated together with their interactions. Various advancedmethods are used, including theory, experiments, numerical modeling and the development ofinnovative measuring instruments. In recent years, new facilities and capabilities have beendeveloped such as the Coriolis platform, the test bench for water turbine models used in the field ofmarine renewable energies and the PREVERO cavitation tunnel for cavitation erosion investigations.

Figure 1 - The Coriolis platform (left), with an example of the velocity field obtained by PIV in a scaled model (horizontal scale 1/100 000) of tidal currents in theStrait of Luzon (right). The ellipses indicate the trajectories of the main (barotropic) tide while the colors represent the excited internal waves (baroclinic tide) alsoseen as a vertical cut in the bottom right (from Mercier et al. 2013 [1])




systems. Other imaging laser techniques canbe used such as LIF (Laser InducedFluorescence). Local probes are also available,like ultrasonic velocimeters, salinity and temper-ature sensors. Mechanical displacements anddata acquisition are computer controlled. Theinstallation is also appropriate for Lagrangianstudies, tracking various flow tracers orparticles.

Recent projects involve the generation ofinternal waves by tidal currents on submarineridges (see Fig. 1). Those can evolve intosolitary waves with intense currents in someregions of the world, a process whichcontributes to the global vertical mixing of theocean. Other projects model the mixing of freshand salty water in a river estuary or a fjord. Morefundamental studies of turbulence in a densitystratified and rotating medium are alsoperformed. The general mechanisms of energydissipation and mixing in oceanic currents arethus investigated, with particular interest in theevolution of coherent vortices like the‘meddies’, lenses of Mediterranean waterpersisting at 1 000 m depth in the Atlantic Ocean. As part ofthe ERC (European Research Council) projectWATU (WAve TUrbulence), surface waves arestudied in the context of wave turbulence, whichis the long-term random behaviour of inter-acting waves of moderate amplitude in anenclosed basin. For this project, the full space-time fluctuations of the free surface shape andflow velocity is obtained by a 3 camera stereo-scopic system. Extensions of these studies to

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Joël Sommeria is seniorresearcher at the FrenchNational Center for

Scientific Research (CNRS). He has beenworking at LEGI since 2000 on geophysicalfluid mechanics, turbulence, statisticalmechanics and flow measurementtechniques.

Thierry Maitre isAssociate Professor atthe Ecole Nationale

Supérieure de l’Eau de l’Energie et del’Environnement (ENSE3). He has beenworking at LEGI since 1997 onturbomachinery and more recently on newconcepts of marine and river currentsenergy converters.

Jean-Pierre Franc issenior researcher at theFrench National Center

for Scientific Research (CNRS). He hasbeen working at LEGI since 1982 onvarious topics including cavitation, two-phase flows and heat transfer.

Fig. 2a - Test section for Darrieus turbinesFig. 2b - Cavitating vortex

internal gravity waves obtained at a densityinterface or in a continually stratified mediumare under way.

The test bench for marine waterturbine models The marine water turbine facility (Fig. 2a) wasbuilt in 2005 in the frame of the HARVEST -Hydroliennes à Axe de Rotation VErticalSTabilisé - project aiming at developing a newconcept of cross flow (Darrieus) marine currentenergy converter [3]. Compared to axial turbines,Darrieus type turbines present several possibil-ities for marine applications. They are insensitiveto the flow direction avoiding the need of yawand variable pitch devices. Moreover, Darrieusturbines can be piled up on a same shaftallowing the use of the same generator for theentire turbine column. The length of thecolumns can be adjusted to fit the water depth.However, unlike axial flow turbines and morelargely the majority of hydraulic turbines, crossflow turbine blades develop dynamic stallsleading to complex vortical and turbulent flows.Because these flows are challenging for thenumerical modelling, the turbine facility hasbeen used following two goals: optimizing theturbine design by using several scaled modelsand checking the ability of numerical modelingto calculate accurately the torque and the flowfield.The test section, shown in Fig. 2a, has a rectan-gular form (length x width x height = 100 x 70 x25 cm3) and is placed downstream aconvergent duct in order to obtain a uniforminflow. A small turbulence level of 1% is

achieved thanks to honeycomb devices placedupstream. The flow rate is up to 0.5 m3/sallowing a velocity range from 1 to 3 m/s. Thelower and the two lateral walls of the test sectionare made of altuglass to allow flow visualiza-tions and PIV / LDV measurements. The upperwall is made of aluminum in order to supportthe experimental apparatus. The measurementplatform (in blue on Fig. 2) is mounted on thesuperior wall by means of four piezoelectricsensors giving the instantaneous hydrodynamicforces applying on the turbine. The torque ismeasured via a frameless permanent magnetservomotor kit mounted above the platform. Itincludes an electrical synchronous generator(red cylinder in Fig. 2a) used to drive the turbineat the desired rotational speed and a resolvergiving the angular position (blue cylinder in Fig.2a). A proportional-integral regulation imposesa constant rotation speed by controlling theelectric current and consequently the instanta-

2a

2b




neous torque applied on the turbine. The tunnelcan be depressurized to allow cavitating flowconditions. In the case of water turbines, thecavitation risk is weak and cavitation is essen-tially used to visualize the strong vortices shedby the blades (Fig. 2b).The straight blade design (Fig. 2b) has beenused for numerical modelling validations. It hasbeen shown that the URANS (UnsteadyReynolds Averaged Navier-Stokes) methodleads to accurate predictions of mean torqueand power at nominal operating point [3]. PIVmeasurements performed locally aroundrotating blades have shown that the dynamicstall is correctly captured by the numericalprediction even if phase shift is observed.Cross-flow turbines recently developed atLEGI [2] are currently commercialized by thestart-up company Hydroquest.

The PREVERO facility for cavitationerosion research and materialtestingThe PREVERO facility (Fig. 3) was built in 2003in order to investigate cavitation erosion. It is ahydrodynamic tunnel whose main feature is thatit can be pressurized up to 40 bars (4 MPa). Asa result, velocities as high as 90 m/s can bereached, which leads to cavitating flows of highaggressiveness. The flow rate can be changedin order to vary the flow aggressiveness andthen investigate the effect of flow velocity, whichis known to be of primary importance incavitation damage. The operating pressure canalso be changed in order to vary the cavitationnumber and the extent of cavitation. The powerof the pump is 80 kW. The test section is

axisymmetric and made of an axial nozzle of 16 mm in diameter followed by a radialdivergent of 2.5 mm in thickness wherecavitation bubbles are produced. The sample tobe eroded is 100 mm in diameter. It is facing thenozzle and exposed to bubble collapses.

Various types of erosion tests can be madeincluding pitting tests and mass loss tests.Pitting tests are short duration tests generallyconducted on metallic alloys whose surface isfinely polished in order to easily identifycavitation erosion pits. Pits are small plasticdeformations of micrometer size that each resultfrom the collapse of a single cavitation bubbleproduced in the test section. Measurement ofpit shape (depth, diameter…) and pitting rateallows the flow aggressiveness to be quantita-tively characterized. In particular, a specialtechnique has been recently developed in orderto determine for each pit the impact load that isresponsible for it.

Mass loss tests can also be conducted. Theyare long duration tests from which the kinetics

of erosion can be determined. Typical mass losscurves are determined that show the evolutionof mass loss as a function of exposure time.Major parameters can be deduced such as theduration of the incubation period and theeventual erosion rate that both characterize thematerial resistance. Any type of material can betested including conventional metallic alloysand new materials such as compliant [4], coatedor composite materials.

In addition to the experimental approach, LEGIdevelops together with the Laboratory ofSciences and Engineering of Materials andProcesses in Grenoble (SIMAP)(www.simap.grenoble-inp.fr) a numericalmethod for predicting cavitation erosiondamage. The method is based on FEM (FiniteElement Modeling) simulations of the responseof the material to the repetitive impact loadsgenerated by the bubble collapses. Theapproach includes a damage criterion tocompute material removal due to cavitation [5].Such a predictive approach, still under devel-opment, represents a breakthrough incomparison to correlative techniques used sofar in cavitation erosion. n

References1. M.J. Mercier et al. (2013) Large-scale, realistic laboratory modeling

of M2 internal tide generation at the Luzon Strait. GeophysicalResearch Letters, Vol. 40, Issue 21, 5704–5709,doi:10.1002/2013GL058064.

2. J.L. Achard, T. Maitre, Turbomachine Hydraulique. Patent n°EP1718863, G-INP, Nov. 8th, 2006.

3. T. Maitre, E. Amet, C. Pellone, Modelling of the flow in a Darrieuswater turbine: wall grid refinement analysis and comparison withexperiments. Renewable Energy, Vol. 51, March 2013, p. 497-512,doi:10.1016/j.renene.2012.09.030.

4. T. Deplancke et al., Outstanding cavitation erosion resistance ofUltra High Molecular Weight Polyethylene (UHMWPE) coatings.Wear, 2015, 328–329, p. 301-308,doi:10.1016/j.wear.2015.01.077.

5. Fivel, M., J.-P. Franc, and S. Chandra Roy, Towards numericalprediction of cavitation erosion. Interface Focus, 2015, Vol. 5,Issue 5, doi: 10.1098/rsfs.2015.0013.

Fig. 3 - The PREVEROfacility for cavitationerosion research andmaterial testing

Velocities as highas 90 m/s can bereached, whichleads to cavitatingflows of highaggressiveness




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OCEAN-STRUCTURE-SEABED MODELLING IN UWA’S RECIRCULATING ‘O-TUBE’ FLUMESBY L. CHENG, S. DRAPER, H. AN & D.J. WHITE

O-Tube conceptMany physical modelling facilities have beendeveloped to study offshore structures,including open channel flumes, U-tube flumes,and oscillating water tunnels. However, each ofthese facilities have limitations for studyingocean-structure-seabed interaction problems instorm conditions, such as that experienced on

Australia’s North West Shelf (NWS). Openchannel flumes, for example, are limited towave velocities below which wave breakingoccurs, whilst the use of a driven trolley in anopen channel allows higher velocities to beachieved but is impractical for large regions ofmobile bed. U-tubes allow higher velocities tobe achieved, but with limited flexibility (due to

the requirement to operate at or nearresonance). Piston driven water tunnels offermore flexible control but are limited by thestroke of the piston.

Because of these limitations an alternativeflume configuration, known as an O-tube, hasbeen developed at the University of WesternAustralia. This flume comprises a horizontalfully enclosed circulating water channel, with arectangular test section and an impeller-typepump driven by a motor. With this arrangementcurrents can be introduced easily and wavevelocities are limited only by the pump charac-teristics and not by wave breaking, resonanceof the water mass or the stroke of a piston.

Three O-tubes have been constructed at theUniversity of Western Australia (see Table andFigures 1-3). The mini O-tube (MOT) wasconstructed first to prove the concept, followed

The University of Western Australia (UWA) is home to a set ofrecirculating water tunnels, referred to as the ‘O-tubes’. Theseflumes have been developed at UWA to allow simulation of ocean-structure-seabed interactions using realistic metocean and geo-technical conditions. The large, small and mini O-tube flumes allowseabed flows to be simulated at a range of scales, including fullscale modelling of small subsea pipelines and scour and sedimenttransport around infrastructure.

Figure 1 - Examining scour around the model pipe in the test section of the Large O-tube




quickly by the large O-tube (LOT). The differentscales of O-tube are suited to differentpurposes. The LOT is capable of modellingsmall pipelines at full scale, with 1:1 scale flowconditions. The MOT and Small O-tube (SOT)require less sediment to fill and nourish theworking section compared with the LOT. Thisallows small scale tests and sediment-specificerosion testing to be undertaken usingprototype sediments gathered from the field.

O-Tube measurement and controlhardwareThe LOT, SOT and MOT all use similar driveand control systems, varying only in scale andpower. Flow is forced around the LOT with animpeller driven by a brushless 580 kW ACmotor. The rotational speed of the motor iscontrolled by a Variable Frequency Drive (VFD)and can be controlled from a desktopcomputer via a signal that is transmitteddigitally over a local wireless network. Theinternal control software on the VFD includessafety interlocks that limit motor accelerationand rotation speed. The SOT and MOT usesmaller drives operating on the sameprinciples.

Flow conditions including steady current,sinusoidal oscillatory flow, random oscillatoryflow and any combination of the above condi-tions can be generated. These flows areachieved by controlling the propeller to run at asteady, oscillating or irregular rotational speed.Detailed studies of motor speed-flow speedrelationships, flow asymmetry, turbulenceintensity and secondary flows have been under-taken in all of the O-tubes (Luo et al. 2011, Anet al. 2013, Cheng et al. 2014 and Mohr et al.2016a).

An important component of the LOT facility is a200 mm instrumented model pipe mounted onan actuator system to record the appliedhorizontal and vertical forces. The pipe is alsoequipped with a network of surface pressurecells to record the hydrodynamic load aroundthe pipe circumference. The actuator systemprevents model pipe movements in unrealisticdegrees of freedom such as roll and yaw. Thefeedback system can provide neutral horizontaland vertical control, allowing the pipe freelateral movement in response to the naturalbalance between hydrodynamic loading andsoil resistance, and free vertical movement as ifacting under self-weight.

In addition to the actuator controlled modelpipe, the O-tube laboratory is equipped withvarious measurement devices. Flow measure-ments within the O-tubes are made usingAcoustic Doppler Velocimeters (ADVs) and anelectrical-magnetic sensor. A two-dimensionalParticle Image Velocimetry (PIV) system can be

used for flow visualization, whilst an acousticecho sounder and contact image sensors areused in various configurations for continuouslydetecting scour around subsea structures. A laser scanner and infra-red profiler have beenadapted to scan three-dimensional scourprofiles. Each of these devices can be used

Figure 2 - General arrangement of the large O-tube (LOT) at UWA’s Shenton Park campus

Figure 3 - A scour profile around two vertical piles recorded using the infra-red 3D camera.

Table 1 - Key characteristics of UWA’s O-tube flumes

Large O-tube Small O-tube Mini O-tube (LOT) (SOT) (MOT)

Year commissioned 2010 2014 2008

Working section dimensions Length, L (m) 17 3.0 2.0

Width, W (m) 1.0 0.3 0.2

Height, H (m) 1.4 0.45 0.3

Maximum steady current (m/s) 3 4.5 1.5

Typical oscillatory flow maximum velocity, 1 – 2.5 1 – 3 0.5Um (m/s)

Period, T (s) 5 – 13 s 4 – 10 s 6 s




synchronously to extract more comprehensivedata, which enables an improved under-standing of fundamental ocean-structure-seabed interactions.

Research activities and researchoutcomesSignificant research efforts have been devotedto pipeline on-bottom stability and seabedmobility at UWA over the past five years,supported by the Australian Research Council(ARC) and industry partners Woodside andChevron through the STABLEpipe Joint IndustryProject (JIP). Model tests in the LOT havehighlighted the strong influence of seabedmobility on pipeline stability. The processes ofscour and self-burial have been observed andquantified in controlled conditions, leading to

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Liang Cheng is a WinthropProfessor at The Universityof Western Australia and a“1000-Talents” Professor atDalian University of

Technology in China. Liang got his BE fromTsinghua University in HydropowerEngineering (1983) and PhD from DalianUniversity of Technology in Hydraulics (1990).Liang has more than 20 years’ experience inresearch areas covering vortex-inducedvibrations, local scour, flow/structure/seabedinteractions and computational fluid dynamics(CFD) modelling. Liang has published widelyin these areas and has been working closelywith industry on consulting and contractresearch projects.

Scott Draper is a seniorlecturer at The University ofWestern Australia (UWA).He completed a DPhil at theUniversity of Oxford, UK, in

2011 working on tidal stream energy. At UWAScott now works more generally in offshorefluid mechanics, applied to both the oil andgas and marine renewable energy industries.His research work focuses on: scour ofsubsea infrastructure at the seabed; theoptimization of arrays marine renewableenergy devices; and wave kinematics andstatistics. Scott has written over 50 peerreviewed papers and presents public lecturesto industry and the wider community.

Hongwei An is a lecturerand DECRA ResearchFellow at the University of Western Australia. He finished his PhD

degree in 2010 from UWA and since then hehas been working at UWA in the offshorehydrodynamics area. His research interestsinclude flow-structure interaction, subseastructure stability, scour and sedimenttransport through both physical model testsand numerical simulations.

David White holds the ShellEMI Chair of OffshoreEngineering at theUniversity of WesternAustralia. He completed

MEng and PhD degrees at CambridgeUniversity before holding a UniversityLectureship in Cambridge until 2006 when hemoved to UWA. His specialism is offshoregeotechnics and his research has led to >250 publications that feature in manyindustry guidelines, shaping engineeringpractice. He is a Fellow of the Royal Academyof Engineering, the Australian Academy ofTechnological Sciences and Engineering andthe Institution of Engineers Australia.

new calculation methods for design purposes.Based on the STABLEpipe JIP, a new designguideline for the stability design for subseapipelines has been prepared (DNV 2015). Thiswork is a team effort involving det NorskeVeritas (DNV) and provides methods forassessing pipeline stability that account forscour and sedimentation over the duration ofthe pipeline operating life.

Besides the stability of subsea pipelines, awide range of research topics related to varioussubsea structures have been investigatedusing the O-tube facilities. These include localscour around pile foundations and caissons,both with and without protection; local scouraround wave energy devices; onset of tunnelscour under subsea pipelines; stability of rock

berms on solid and erodible seabed; stabilityof concrete/steel mattress on the seabed;erosion properties of various sediments, andestimation of hydrodynamic force on offshorestructures. This work has been captured in over20 academic publications, including multiplehigh impact journal publications in CoastalEngineering and the Proceedings of the RoyalSociety (An et al. 2013; Draper et al. 2015;Mohr et al. 2016b). Full details of the publica-tions can be found on the UWA website (such as http://www.web.uwa.edu.au/people/liang.cheng).

Research outcomes from the O-tube havecontributed directly to the oil and gas industry,through industrial and contract researchprojects. Experimental work in the O-tubes hasalready supported engineering design of morethan 10 developments in locations includingoffshore Western Australia, the North Sea andIndonesia. This work has resulted in significantcost savings to the operators. The O-tube facil-ities also enable new fundamental research. Inthe last five years the team have received fourAustralian Research Council Grants from theirDiscovery and Linkage schemes. The O-tubefacilities have also been used to supportstudent research, including 5 PhD projects andmore than 40 final year undergraduate andmaster degree projects at UWA.

AcknowledgementsDevelopment of the O-tube flumes at UWA hasbeen funded by Woodside, Chevron, theAustralian Research Council and UWAStrategic Funds. The technician team has beenmaking a great contribution to the researchwork. The technician team (Mr. T. Brown, Mr. J.Breen, Mrs W. Sun, Mr. A. Duff and Mr. P. Hortin)is acknowledged. Mr. Y. Wu is acknowledgedfor processing some photographs used in thispaper. n

ReferencesAn, H., Luo, C., Cheng, L., & White, D. (2013). ‘A new facility for

studying ocean-structure-seabed interactions: The O-tube’.Coastal Engineering, 82, 88-101.

Cheng, L., An, H., Draper, S., Luo, H., Brown, T. and White, D. (2014)‘Invited Keynote: UWA’s O-tube facilities: physical modelling offluid-structure-seabed interactions’. Int. Conf. on PhysicalModelling in Geotechnics, Perth, Australia, 3-20.

DNV (2015) Stablepipe Guideline. Report. PP103289-001 (confi-dential to JIP participants)

Draper, S., An, H., Cheng, L., White, D.J. and Griffiths, T., 2015.Stability of subsea pipelines during large storms. PhilosophicalTransactions of the Royal Society of London A: Mathematical,Physical and Engineering Sciences, 373(2033), p.20140106.

Luo, C., An, H., Cheng, L., White, D. (2012), 'Calibration of UWA’s O-tube flume facility', 31st International Conference on Ocean,Offshore and Arctic Engineering, USA, CD, pp. 11pp

Mohr, H., Draper, S., White, D.J., Cheng, L., An. H and Zhang, Q.(2016a) ‘The hydrodynamics of a recirculating (O-tube) flume’,International Conference on Scour and Erosion, Oxford, UK.

Mohr, H., Draper, S., White, D.J. & Cheng, L. (2016b). Predicting therate of scour beneath subsea pipelines in marine sedimentsunder steady flow conditions. Coastal Engineering, 110, 111-126.




the safety margin or failure probability isevaluated. The tsunami loads and the responseof structures are predicted by combiningnumerical models and empirical equations.Data obtained from large-scale experiments onthe fragility of structures against tsunami impactare useful for the verification of numericalmodels and empirical equations. Furthermore,the performance of tsunami prevention struc-tures can be confirmed through large-scaleexperiments.Laboratory experiments on tsunami impacthave conventionally been carried out usingflumes with four types of wave generators:

piston-type wave generators, pump wavegenerators, pneumatic wave generators, andgate-rapid-opening generators, i.e., dam breakflows. As experienced with the 2004 IndianOcean tsunami and the 2011 Tohoku earth-quake tsunami, tsunami inundation flows havecomplex waveforms with a long duration. It isdifficult to reproduce and control such a realistictsunami inundation flow on a large scale usingthese generators because of limitations of thestroke length of the wave-generating paddles,the performance of pumps, the length offlumes, and the degree of freedom in thecontrol of the flows.

LARGE-SCALE TSUNAMI PHYSICAL SIMULATOR A NEW TYPE OF EXPERIMENTAL FLUME FOR RESEARCH ON TSUNAMI IMPACT BY NAOTO KIHARA

Tsunami impact and experimentsThe tsunami caused by the 2011 Tohoku earth-quake struck a wide area of the northeasterncoast of Japan. The earthquake and tsunamiresulted in more than 15 000 deaths, over 2 000missing people, and the destruction of a largeamount of infrastructure. For disaster preventionand the mitigation of tsunami damage in coastalareas of Japan, it is necessary to assess thefragility of coastal structures against tsunamis.In the fragility assessment of a coastal structure,the loads due to probable tsunamis, theresponse of the structure to the loads, and thecapacity of the structure are predicted, and then

For tsunami disaster prevention and mitigation in coastal areas, it is important to assess the safetymargins or failure probabilities of coastal structures against tsunamis by predicting the tsunamiloads and the response of the structures. Data obtained from large-scale experiments on tsunamiimpact are useful for the development of evaluation technologies. A Large-Scale Tsunami PhysicalSimulator was designed for large scale experiments with realistic tsunami inundation flows, andwas installed at the Central Research Institute of Electric Power Industry.

Figure 1 - The photograph (a) and the schematic view (b) of the Large-Scale Tsunami Physical Simulator Figure 2 The schematic diagram of the method used to control the flow. (a modified version of Fig. 1 in Ota et al. [2013])

a

b




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and 0.3 m width was set on the flat bottom inthe flume. We measured vertical profiles of thepressure on the front of the seawall ininundation flows with periods longer than 80 s(Figure 3). This experiment showed in detail thecharacteristics and types of tsunami wavepressure profiles in terms of their change withtime. The second experiment was on the forceof debris collision (Takabatake et al., 2015). Thedebris used in the experiment were wood logsand an actual mini vehicle. A vertical steel plate,which was designed to be able to measure thecollision force, was set in the test unit. Thedebris were initially set upstream of the plateand allowed to drift in the bore, and collide withthe plate. The experiments with the mini vehicleshowed that the relationship between theimpact speed and the collision force wasnonlinear and that the axial stiffness dependedon the impact speed. These experimentalresults provide useful knowledge for the designand fragility assessment of tsunami preventionstructures. n

ReferencesKihara, N., Niida, Y., Takabatake, D., Kaida, H., Shibayama, A., and

Miyagawa, Y., 2015. Large-scale experiments on tsunami-inducedpressure on a vertical tide wall. Coast. Eng. vol.99, pp. 46–63.

Ota K., Kihara N., Sato T., Takabatake D., Matsuyama M., Yosii T. andTanaka N., 2013. A physical simulation method for tsunamiinundation flow with arbitrary flow velocity and inundation depth, J.JSCE, Ser. B2, Coast. Eng., vol.69, pp. I_471-I_475. (in Japanese)

Takabatake, D., Kihara, N., Miyagara, Y., Kaida, H., Shibayama, A. andIkeno, M., 2015. Axial stiffness model for estimating floating debrisimpact forces due to tsunami, J. JSCE, Ser.B2, Coast. Eng. vol.71,No.2, pp. I_1015-I_1020. (in Japanese).

wide, and 2.5 m high. To observe measure-ments from the lateral face of the channel, fouracrylic observation windows, 0.9 m × 0.9 m insize, were installed in the side wall. There is a pitof 1 m depth beneath the bottom of the test unitfor use in scouring experiments. Eight valvesare mounted on eight pipes that connect thehead tank and the control unit. A radial steelgate separates the control unit and the test unit,and a moving steel weir separates the test unitand the water storage tank. To control atsunami-like inundation flow in the test section,the apertures of the eight valves and the heightsof the gate and weir are controlled by computer.A schematic diagram of the method used tocontrol the flow is shown in Figure 2 (Ota et al.,2013). A tsunami bore is generated by rapidlyopening the radial gate like a dam break flow.The inundation depth of the bore is controlledby the height of the gate. The velocity of thebore is controlled by the water depth in thecontrol unit. The velocity and depth of a fast floware controlled by the height of the gate and thevalve aperture. A tranquil flow is controlled bythe top height of the weir and the valve aperture.This tsunami generation method makes itpossible to reproduce “inundation tsunami”-likeflows in the test section.

Experiments on tsunami impactAfter the facility was installed, some experi-ments on tsunami impact were carried out, andtwo of them are briefly described hereafter. Thefirst experiment was on tsunami wave pressureloading on a seawall (Kihara et al., 2015). In thisexperiment, a vertical seawall with 1.5 m height

Naoto Kihara started working at CentralResearch Institute of Electric PowerIndustry in 2006 after receiving a doctor’sdegree in science at Kyoto University. Inthe first five years of his career he carriedout research on ocean waves, seasalttransport in the atmosphere, and tsunamis.After the 2011 Tohoku earthquake andtsunami, his main area of research becamethe tsunami impact and fragility evaluationof coastal facilities against tsunamis. Hewas the leader of the team that designedand installed the Large-Scale TsunamiPhysical Simulator.

Our main research target is fragility assessmentin areas of inundation. Thus an importantrequirement for experimental facilities is thegeneration and control of realistic tsunamiinundation flows. A new experimental facility,called “the Large-Scale Tsunami PhysicalSimulator” installed in the Central ResearchInstitute of Electric Power Industry (CRIEPI),Japan, was designed to be able to generateand control various types of local tsunamiinundation flows on a large scale.

Design of the Large-Scale TsunamiPhysical SimulatorFigure 1 shows a photograph and schematicview of the Large-Scale Tsunami PhysicalSimulator. This facility is composed of a headtank, a control unit, a test unit, and a waterstorage tank. The maximum water volume of thehead tank is 650 m3, and its maximum depth is6.5 m. The control unit is a closed rectangularchannel. The test unit is an open channel madeof reinforced concrete that is 20 m long, 4 m

Figure 3 The experiment on tsunami wave pressure loading on a seawall

This tsunami generation methodmakes it possibleto reproduce“inundationtsunami”-like flowsin the test section




The technology of Particle Image Velocimetry(PIV) can be used to measure simultaneouslyand instantaneously velocities over an entirefield. Fujita (1998) used the PIV technique tomeasure velocity distributions in a wide range ofconditions. Since the PIV algorithm is compli-cated, the time required to calculate themeasured velocity distribution is large, whichmakes real-time measurements of broadvelocity distribution fields hard.

A branch of the PIV technology is ParticleTracking Velocimetry (PTV). Because of itssimple algorithm and fast computation, it ismore practical to use PTV to measure thevelocity distribution over large fields in hydraulicmodel experiments. A velocity distributionmeasuring system developed based on PTV,has been used in physical model experiments(Xingkui Wang, 1996). The images recordedand stored on video tape, are processed afterthey have been collected, and then the requiredcalculations and analysis are performed by thesystem. This makes it hard to use this approachfor real-time measurements. The developmentof monitoring cameras has made it possibletoday to obtain real-time measurements of thevelocity distribution over large areas(Mingzhong Yu, 2002). However, the data trans-mission of the cameras is limited by bandwidth,and it is not possible to synchronize thecollection and transmission of data frommultiple cameras. Consequently, the method ofcollecting images introduces cumulative errorsleading to incorrect results when velocitymeasurements over large areas are combined.Beijing Sinfotek Technology Co., Ltd (Sinfotek)has developed a large-scale synchronousvelocity measuring system based on the PTVtechnology. The system can obtain quickly andaccurately the flow field in a model test, as wellas the flow velocity distribution on crosssections, and the velocity history at single ormultiple points. The system has solved theproblem of multi-camera collecting imagessimultaneously, and has improved the synchro-nization of collecting images greatly. (SinfotekOpen Patent No.: CN100487372C). In order to

A LARGE SCALE SYNCHRONOUSVELOCITY MEASURING SYSTEMBASED ON THE PTV TECHNOLOGYBY JUN ZHENG, MINGXUAN REN, XIHUA WANG AND ZHAOSONG QU

measure the velocity distribution over largeareas the system was further improved by usingLocal Area Network (LAN) technology. Thesystem has been used widely in hydraulicmodel experiments in many scientific researchinstitutes and universities.

Key TechnologyAcquisition TerminalThe system uses high-resolution ChargeCoupled Device (CCD) cameras for image



acquisition. Cameras are installed above thehydraulic model. The vertical distance of eachcamera from the model is determined by therange of measurements. When the camera isinstalled at a fixed height above the model, thenumber of cameras can be calculated based onthe size of model and the vertical distance fromthe camera to the model. The system uses optical fiber and cable tosample images, and then transfers the imagesto a computer for processing.

Figure 1 - Yangtze River flood control model

Figure 2 - Flow field result of engineering design scheme

Dr Jun Zheng started work-ing in Sinfotek in 2008, incharge of different projectsand research in areas related to water science,

measurements of river hydraulics, sedimenttransport and fluid mechanics.

Zhaosong Qu is the presi-dent of Sinfotek, a speciallyinvited expert under the national “Thousand TalentsPlan”, and professor of

Chongqing Jiaotong University. His researchfocuses on flow, sediment transport measurement of water and environmental science.

Dr Xihua Wang has morethan 10 years of experi-ence working in softwaredevelopment and algorithmresearch. Her interest

areas are related to image processing, ultra-sonic measurements and high performancecomputing.

Mingxuan Ren is a SeniorProduct Manager of the hy-draulic measuring system.He began his professionalcareer in Sinfotek in 2007.

His current fields of interest are image processing and the auto-control of flow andsediment movement.


control a “server”, which controls the entiresystem.

ApplicationThe system has been widely used in hydraulicmodel experiments for rivers and harbors, aswell in various flume experiments. Many univer-sities and research institutes in China, such asTsinghua University, Yangtze River ScientificResearch Institute, Nanjing Hydraulic ResearchInstitute and Wuhan University, have used thesystem.

ConclusionThe technology of Particle Image Velocimetry, anon-contact and high-precision velocitymeasurement technique, is widely used in

hydromechanics. A system developed basedon the technology of PTV has been applied toreal-time measurements of the velocity distri-bution over large areas. The system has solvedthe problems of synchronization and expansion,which has improved greatly the accuracy ofvelocity measurements, and expanded thescope of its applications. n

ReferencesFujita I., Muste M. and Kruger A, (1998). Large-scale Particle Image

Velocimetry for flow analysis in hydraulic engineering applications.Journal of Hydraulic Research, 1998, 36(3):397-414 [32]Greimann B.

Xingkui Wang, Dongming Pang, Guixian Wang, et al. (1996),Application of Image processing technology in the physical modelexperiments velocity distribution measurement. Journal ofSediment Research, 1996, (4):21-26.

MingZhong Yu. (2002) Study on the PTV Technique and 3D Movementof Particles [D]. Beijing: Tsinghua University,2002

Software AlgorithmThe software system uses image processing torecognize individual particles and extract theircoordinates. Then, the system processessequences of images matching individualparticles. The coordinates of matched particlesare used to calculate their velocity.The system uses the method of adaptivethreshold to achieve image segmentation, thepurpose of which is to recognize individualparticles. The pixels belonging to differentparticles are divided into groups, one group perparticle. Each group contains a few pixels. The center coordinate of a particle is calculatedbased on the coordinates of all the pixels in agroup.

Local Area Network (LAN) ExtensionIt is very difficult for a standard system (16cameras) to meet the needs of large models. Inthis regard, the system is expanded using aLAN.With this expansion, the system can measurethe velocity distribution over large areas. Theexpanded system consists of a number ofstandard systems. The standard systemscommunicate with each other via 1 or 10 GigabitLAN. All the standard systems aggregate intoone network edition system. Any of the standardsystems can play the role of “server” or “client”.The "server" sends instructions to the "client",receives the velocity data from the "client", andthen merges and saves the velocity data. The"server" also has other functions, such as, real-time monitoring of each channel of the "client"adjusting the threshold of each channel settingparameters and so on.

In order to make the system more integrated,the “client” and the “server” are packaged in acabinet. To perform simultaneous velocitymeasurements the operator only needs to

IAHRH Y D R A U L I C LABORATORIES S P E C I A L


Figure 3 - The real scene of bend model test Figure 4 - The flow field measurement result of bend model test

In recent years there has been an increasedfocus on the islands Lolland and Falster inSouthern Denmark because of the fixedimmersed Fehmarnbelt tunnel betweenDenmark and Germany that is planned to beconstructed in the near future. This focus hasresulted in increased research activity,especially in connection with the environmentalinvestigations prior to the construction works. Inconnection with these investigations theRødsand lagoon was studied intensively as itwas pointed out as a sensitive area during theconstruction phase. Rødsand lagoon is desig-nated as a Natura 2000 area. Natura 2000areas are part of a network of European natureprotection areas aiming at the protection ofspecific nature types and endangered andprotected species.

The Rødsand laboratory was established in2009 as a result of ongoing activities in the areaand the desire for coordination of the efforts tostudy the area. The laboratory has severalpurposes including:• Study and exploration of the Rødsand area(land, lagoon and near-shore)

• Utilization of the area as a test for differenttypes of equipment

• Utilization of the abundant field data for devel-opment of better numerical modelling tools

• Use of the area and its facilities for arrangingcourses, seminars and other activities

The Rødsand lagoon is a non-tidal lagoon in theinner Danish Waters (Figure 1). The area islocated next to Fehmarnbelt and is protected bya coastal spit, as well as by two semi-submerged sand barriers. The lagoon is locatednorth of the strait Fehmarnbelt. Water exchangewith Fehmarnbelt takes place through threeopenings towards the South. The water levelvariation is forced mainly by water level changesin Fehmarnbelt. Fehmarnbelt itself is part of theinner Danish waters. These waters form atransition zone between the salty North Sea andthe brackish Baltic Proper. Fehmarnbelt isresponsible for 70-75% of the water exchange.The water level variations in the inner Danishwaters are caused by meteorological changesrather than actual tides. Rødsand lagoon alsohas an opening towards the North,Guldborgsund which occasionally contributes tothe water exchange.

The laboratory itself consists of a farm housewith lodging facilities as well as a smalllaboratory and room for instrument testing andstorage. In addition, three instrument platformshave been erected in the lagoon (Figure 2).These platforms are prepared with fuel cells anddata communication units. This allows the usersto fairly quickly install any instrument to theplatform and to retrieve data online. Whenneeded, the platforms are equipped withremotely controlled water samplers ensuring awater sampling programme that covers a rangeof weather situations. Additionally one buoystation has been established in the eastern partof the lagoon (Figure 1).

Monitoring the physical environment A large data set has been collected partly inconnection with baseline investigations prior toestablishing the Fehmarnbelt fixed link andpartly to support a collaborative research efforton bio-geophysical processes and landscapedynamics in a non-tidal coastal lagoon. Basedon four online stations in the lagoon, the dataset consists of numerous parameters including:hydrodynamics, suspended sediment concen-trations, sediment grain size/floc size distribu-tions, light attenuation coefficients, organic

THE RØDSAND LABORATORY – A WORKING LABORATORY IN THE FIELD BY ULRIK LUMBORG

A joint effort has resulted in a field laboratory in Rødsand, in the southern part of Denmark. The areais now being used by a number of national and international partners to conduct cross-disciplinaryresearch. Among the results of the work at Rødsand are an increased understanding of couplingbetween sediment dynamics and benthic biology.

Figure 1 - Position of the monitoring stations

Figure 2 - Technician working on a survey platformin Rødsand lagoon. A total of three towers havebeen erected for easy mounting of monitoringinstruments. The remotely controlled watersampler can be seen in the foreground




The data collection programme was supple-mented with grain size analyses of the bedmaterial and mapping of benthic flora andfauna. The data set covers a period of nearlytwo years and allow for a range of studies onbiology and sediment dynamics. The exampleprovided in Figure 3 shows total suspendedmatter concentrations, the grain size as well aswind characteristics. It can be seen that thegrain size distribution is correlated with theconcentration and the wind in a rather complexmanner. In general the mean grain sizeincreases with increasing concentration, as flocformation is favoured in this situation. Themedian grain size is however also closely linkedto the wind and can decrease with increasing

wind due to floc breakup. As the monitoringarea is fairly shallow the grain size is mainlygoverned by the wind. These findings areincluded in a larger research project on floccu-lation of fine-grained sediments.

Advancing the activitiesThe survey platforms and the house is nowused by several parties including the Universityof Copenhagen which engages several PhDand Master Students. The laboratory has alsorecently been used by the Hydralab+ researchproject for a study of the coupling betweensediment dynamics and benthic biology. Thisincludes mapping of eelgrass distribution(cover, density, biomass, shoot length),deploying of small high-frequency pressuresensors to monitor wave height, monitoringturbidity, monitoring small scale sedimentaccumulation and erosion and sedimentcharacterization. Subsequently, experimentalsites within seagrass and un-vegetatedsediment will be set up for quantification ofbioturbation using tracers. The collected data will be used to improveexisting modelling tools. The overall character-istics of the sediment size distribution in thelagoon are diverse and depending on theinterplay between wave activity and the waterdepth. Aggregate formation and floc stabilityvary with water depth and hydrodynamics, andsediment modelling must be able to considervariable settling and erodibility characteristics ofboth cohesive and non-cohesive material.Emphasis will be given to the development of amodel that can handle both types of sediment.Another example of a new model developmentis a numerical model that covers both benthicbiology and cohesive sediment. There is goodevidence about how suspended sedimentaffects different sea grasses and fauna. Howbenthic biology affects the sediment dynamicshas also been studied, e.g. how the sea grassbeds are acting as sediment traps and howbiofilms can stabilise the sediment bed. Basedon these field studies an attempt will be madeto construct a numerical model that takes intoaccount both features.After denoting Rødsand lagoon an actual fieldlaboratory the basic research in the area hasincreased and is now used commonly fordifferent interdisciplinary research activities. n

References Guidelines for the establishment of the Natura 2000 network in the

marine environment. Application of the Habitats and BirdsDirectives (2007) at <http://ec.europa.eu/environment/nature/natura2000/marine/index_en.htm>

Sayin, E. & Krauss, W. A numerical study of the water exchangethrough the Danish Straits. Tellus A 48A, 324–341 (1996)

Users Guide to Physical Modelling and Experimentation: Experienceof the HYDRALAB Network. (CRC Press, 2011)

content and local meteorological conditions. The data were collected with a series of highquality instruments.

Current speed- and direction were measuredusing RDI 600 and 1200 kHz kHz WorkHorseADCPs. The Acoustic Doppler Current Profiler(ADCP) measures the current parameters inbins throughout the water column. The profiler isinstalled in a bed frame and measures usingacoustics. In this way the currents are monitoredwithout influencing the water movement. Theinstruments are ideal for monitoring over longerperiods.Water quality parameters were monitored usingthe WQM manufactured by WET Labs. The multiparameter probe measures pressure, conduc-tivity, temperature, turbidity, fluorescence anddissolved oxygen. The instrument is efficient tomonitor in areas where biofouling can be anissue. The instruments are manufactured incopper on which no fouling occurs. The windowfor fluorescence and optical backscatter isprotected by a “bio wiper” also in copper. Thebio wiper is only open when the measurement istaken. When the instrument is in sleep mode thewiper completely covers the window which canremain clean for a very long time.Grain size distributions were measured usingthe LISST-100X manufactured by SequoiaScientific. The instrument measures turbiditybased on transmissiometry and also the grainsize distribution in 32 classes in the interval 2.5 – 500 µm. The instrument provides reliablemeasurements and is easily operated in marinewaters. Light attenuation was measured using LI-CORlight meters. Using two instruments plus oneabove water the light attenuation can becomputed. The instruments are reliable to use inmarine water but suffers quickly from biofouling.All attached instruments were powered by abattery that was charged by solar panelscombined with an EFOY fuel cell whenevernecessary. The measured data were collected ina data communication unit on the platform andall data were transferred by a mobile internetconnection. The data were collected in the DHIdata management system DIMS and displayedon a web page in near real time for convenientdata QA and inspection. The online data optionwas also used to decide when to trigger theremotely controlled water samplers, e.g. whenturbidity was increasing the user could chooseto start sampling with a fixed interval. Thesampled data were documented by more than200 water samples collected in a range ofweather conditions.

IAHR

Ulrik Lumborg started working for DHI in2005 after finishing a PhD from University ofCopenhagen on modelling of cohesive sediment dynamics. In the first years Ulrikfocused on numerical modelling issues. After some years he became involved withsurvey work and has since studied a number of sites based on a combination ofmonitored data and numerical modelling.His main works during the recent years hasbeen with the environmental impact assess-ment of the Fehmarnbelt fixed link as wellas spill monitoring on dredging projectsthroughout Europe. Since 2012 Ulrik has ledthe Rødsand Laboratory.

Figure 3 - Example of collected time series atstation NS04 in the western part of Rødsandlagoon. Note that the grain size generallydecrease on increasing sediment concentration.This is because of the relatively shallow waterdepth where waves are responsible for resus-pension hence the increased concentrations.These waves also destroy flocs




paddles 60 cm wide, with maximum wave frontlength equal to 28.8 m and maximum height 30 cm.As an example, the basin for off-shore physicalmodels was used in a National InterestResearch Program to analyse tsunami wavesgenerated by landslides in water, the mechanicsof wave generation and propagation, the devel-opment of forecasting tools and the real-timewarning systems based on tidal measurements(for further details, please see Di Risio et al.,2008 and visit the following page of the IAHRMedia Library: http://www.iahrmedialibrary.net/stromboli-islandtsunami-1/).

2. Two wave channels, which are 2.4 m wide, 50 m long and 1.2 m deep. They are equippedwith a two-dimensional wavemaker with onemodule, 4 paddles, each 60 cm wide, providinga maximum wave height of 30 cm (figure 4). For further details, see for example De Serio andMossa (2013).

3. Very large flume for sea currents

The very large flume (figure 5) consists of arectangular steel channel, with base and lateralwalls of 15 mm thick transparent glass material,connected and sealed internally with watertight

silicone rubber, able to prevent thermaldilatation. The base has a surface of 15 m by 4 m and the depth of the channel is 0.4 m. Tocreate a current inside the channel, a closedhydraulic circuit was constructed. The water issupplied by a large metallic tank with acentrifugal electro-pump downstream whichsucks the water into a 200 mm diameter steelpipe. The same water is then discharged intothe upstream steel tank. A side-channel spillwaywith adjustable height made from differentplates mounted together is fitted into theupstream tank. The water that overflows isdirected into a pipe with a 250 mm diametersimilar to that used for the water supply andparallel to it, and is finally discharged into thetank downstream of the channel. Two differentelectromagnetic flowmeters are mounted ontothe two parallel pipes described above in orderto measure the flow rate in the channel as thedifference between the two discharge measure-ments. The upstream and downstream gatescan be used to control the channel flow.

The very large flume is used to study differentenvironmental problems such as wastewaterocean outfalls. While there are several studies inthe literature on nonbuoyant and buoyant jets

THE COASTAL ENGINEERING LABORATORY (LIC) OF THE TECHNICALUNIVERSITY OF BARI – ITALYBY MICHELE MOSSA

The Coastal Engineering Laboratory (LIC) of theDepartment of Civil, Environmental, Building

Engineering and Chemistry of the TechnicalUniversity of Bari was designed for advancedresearch and technical support to the PublicAdministration in coastal territorial management.The LIC was financed by the EU (EuropeanUnion) and the Apulia Region (so-calledProgramma Operativo Plurifondo Puglia – D.R.29/10/90 n. 6155, Structural Funds CEE-REG.CEE n. 20522/68 e 4253/88, Sottoprogramma 6,Misura 6.3). The construction of the laboratorywas completed and started operating inFebruary 2001. The mission of the laboratory is to provide facil-ities for researchers, PhD and MSc-students, aswell as to perform practical work and demon-strations in support of teaching at the University.It also has the potential for physical-experi-mental research in the fields of Maritime andEnvironmental Hydraulics.The core activities of the LIC are managing,procuring and maintaining the facilities andequipment in the laboratory. These activitiesalso include setting up, performing andprocessing of measurements in experiments, aswell as developing the required numericalcodes. Furthermore, the laboratory providessupport to the design and construction of exper-imental facilities, specific installations, apparatusand equipment.The laboratory has a total surface area of 30 000 m2, a laboratory area of 12 000 m2 andan office area of 500 m2 of 5 000 m2.

The laboratory has several wave basins andchannels. The major experimental facilities atLIC are: 1. Two tanks used for three-dimensionalphysical models for maritime and coastalengineering research. The model area consistsof two large basins; one (figures 1 and 2) usedfor coastal modelling and the other for offshoremodelling (figure 3). The coastal model basin is100 m long, 50 m wide and 1.2 m deep (figure2), while the offshore model basin is 50 m long,30 m wide and 3 m deep. The coastal modelfacility is equipped with a series of three-dimen-sional wave makers, having 6 modules, 8

Figure 1 - The basin for coastal physical models

Figure 2 - View of the LIC with the basin forcoastal physical models

Figure 3 - Basin for off-shore physical models




4. Positive and negative buoyant jet systemsA physical model for the study of buoyant jetswas constructed at the LIC. The channel flowpermits to simulate sea currents interacting withbuoyant jets issued in the same channel throughdiffusers with different number of nozzles. Thischannel includes a buoyant jet thermal-hydraulicsystem. The discharged heated water gener-ating the turbulent buoyant jet is pumped intothe channel through a round steel tube mountedat the bottom of the channel in the central longi-tudinal section.

A process computer and control software (thatoversees all the system and stores the test data)can be used to control and manage the buoyantjet system. They can generate the desired jettemperature and flow rate issued into the verylarge channel (Figure 6). Recently anotherapparatus for the analysis of the dilution of saltjets was constructed.

The LIC has many advanced equipment andinstrumentation for morphological andhydraulics analysis, such as: bottom propellers,Acoustic Doppler Velocimeter (ADV), Vessel-Mounted Acoustic Doppler Current Profiler (VM-ACP), micro whirls flow meters, pressuregauges, bottom profiler, densimeter, ultrasonicwave height meter, high-precision GPS trans-ceivers, spectrometer, LDA (Laser DopplerAnemometer) system. Figure 7 shows the newLDA system.

In addition to the specific pieces of equipmentand instrumentation discussed above, thelaboratory is also equipped with software anddata acquisition systems for the study of the

wave climate hindcasting and forecasting, wavepropagation, storm and swell activity insideharbours, solid transport, beach evolution (alsowith remote sensing, see for example Bruno etal. 2016), circulation currents and pollutantdiffusion.”.

The LIC hosts also equipment of the colleaguesof the mechanical engineering department ofthe Technical University of Bari, such as a windtunnel and an experimental apparatus todetermine the performance of pumps andturbines.

The LIC staff includes many researchers, techni-cians and students whose hard work makes thelaboratory a reference point in the field ofHydraulics, Maritime and EnvironmentalHydraulics. The LIC promotes relationships andcooperation with international universities andresearch institutions.

ReferencesWeb site: http://www.iahrmedialibrary.net/stromboli-island-tsunami-1/ Ben Meftah M, De Serio F, Malcangio D, Mossa M, Petrillo AF (2015).

Experimental study of a vertical jet in a vegetated crossflow.Journal Of Environmental Management, vol. 164, p. 19-31, ISSN:0301-4797, doi: 10.1016/j.jenvman.2015.08.035

Bruno M.F., Molfetta M.G., Mossa M., Nutricato R., Morea A. andChiaradia M.T., Coastal Observation through Cosmo-SkyMedHigh-resolution SAR Images, Journal of Coastal Research, 2016.

De Serio F, Mossa M (2013). A laboratory study of irregular shoalingwaves. Experiments In Fluids, vol. 54, ISSN: 0723-4864, doi:10.1007/s00348-013-1536-0

Di Risio, M., P. De Girolamo, G. Bellotti, A. Panizzo, F. Aristodemo,M.G. Molfetta, and A.F. Petrillo (2008), Landslide generatedtsunamis runup at the coast of a conical island: new physicalmodel experiments, J. Geophys. Res.

Mossa M (2004a). Behavior of Nonbuoyant Jets in a WaveEnvironment. Journal Of Hydraulic Engineering, vol. 130, no. 7, p.704-717, ISSN: 0733-9429, doi: 10.1061/(ASCE)0733-9429(2004)130:7(704)

Mossa M (2004b). Experimental study on the interaction of non-buoyant jets and waves. Journal Of Hydraulic Research, vol. 42, p.13-28, ISSN: 0022-1686, doi: 10.1080/00221686.2004.9641179

IAHR

Figure 4 - One of the wave channels

Figure 5 - The very large channel of the LIC

Michele Mossa isfull professor ofHydraulics at theDepartment ofCivil, Environmen-tal, Building Engi-

neering and Chemistry of the TechnicalUniversity of Bari and Chief Scientist of theLIC (Coastal Engineering Laboratory).The main topics of Michele Mossa’s re-search group are relevant with the Environ-mental and Maritime Hydraulics, examiningthe mechanisms of waves, sea currents, local erosion phenomena, buoyant andnon-buoyant jets issued in steady or waveenvironment or in crossflow, also withmacroroughness at the bottom (ripples orvegetation), channel flows and their localphenomena, such as hydraulic jumps.For further details, please visit the website www.michelemossa.it

Figure 6 - Buoyant jet thermal-hydraulic systemwith the process computer

Figure 7 - The laser Doppler anemometer of theLIC

and their interaction with currents, few deal withjet-wave interaction. The majority of studiesemphasizes the importance of a wave flow fieldin diffusion processes and the need for experi-mental tests to better understand jet-wave inter-action dynamics and possibly confirm thevalidity of proposed mathematical models.Although stagnant ambient conditions are ofinterest, they are almost never present in realcoastal environmental problems, where thepresence of waves or currents is common. As aresult, jets cannot be analyzed without consid-ering the surrounding environment, which is onlyrarely under stagnant conditions. This studydeals with this problem and, for example, showsexperimental results of a turbulent non-buoyantjet discharged in a stagnant ambient and in thepresence of a wave flow field in order tocompare both conditions and to experimentallyanalyze the behavior of different flow regions.For further details on the interaction of jets withwaves see Mossa (2004a; 2004b).

A problem investigated in the very large flume isthe effect of corrugated and vegetated channelbeds on buoyant or non-buoyant turbulent jets,vertically discharged into a crossflow. The mainaim of this research is to study the backgroundturbulence, generated by corrugated orvegetated channel bed surfaces, which affectthe jet behavior (i.e., jet penetration, spreading,mixing performance, turbulent structures). Forthe interaction of jets with a vegetated crossflow,see for example Ben Meftah et al. (2015).

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hydro link - Walter Scott, Jr. College of Engineering...4 hydrolink number 1/20 16 Dear Colleagues, The past few months since I assumed the office of President have been a cdeep immersion