2015-2016 Fall AKM 204E FLUID MECHANICSkircave/fluid_mech/fld_mech_ppt.pdf · 2015-2016 Fall AKM...

2015-2016Fall

AKM204EFLUIDMECHANICS

CRN22961Instructors:V.Ş.ÖzgürKIRCA

kircave@itu.edu.tr

FLUIDSSOLIDS

Borrowed from: http://trivedichemistry.com/WebMovie/1Chap1.htm

THE CARCRASH PROBLEM

Cansolids “flow”?

THE CARCRASH PROBLEM

Vcar=18m/s

III

III

Borrowed from: http://www.geekologie.com/2007/04/mclaren-f1-crash-test.php

THE CARCRASH PROBLEM

0

5

10

15

20

0 1 2 3 4 5

V(m/s)

t (s)

Vı

Vıı

0

5

10

15

20

1.98 2 2.02 2.04 2.06

V(m/s)

t (s)

Vı

VııaI>>aII !

CHANGE IN THE VOLUME OFACONEBY PARTIALDERIVATIVES

▸ Classification of Forces:

1. Surface Forces —> Stresses (force per unit area)

A. Normal Stress

B. Shear (Tangential) Stress

2. Body Forces

FUNDAMENTAL EQUATIONS OF FLUID MECHANICS

�!F = m ·�!K

F = � ·An

F = ⌧ ·At

V.Ş. Özgür Kırca kircave@itu.edu.tr

WHATWEHAVESEENSOFAR:

1. UnitSystems (SI,MKfS,…)

2. DimensionalHomogeneity

3. EmpiricalEquationsvs.TheoreticalEquations

4. SpecificMass&SpecificWeight

5. SolidMechanicsvs.FluidMechanics• PhysicalPropertiesofFluids• ContinuumAssumption• Flow=AdditionalNon-linearTermstoAcceleration*

6. Forcesonabody

WHATWEWILLSEETODAY:

1. Viscosity(Fluidresistanceagainstshearstress)• Newton’sLawofViscosity• Newtonianvs.Non-newtonian Fluids• ExpressionsofKinematicandDynamicViscosity• ViscosityinLiquidsandGases

à External ForcesonaBodyà StressonaPoint(reviewataglance)

2. Statics,KinematicsandDynamics

3. Compressibility (Fluidresistanceagainstnormalstress/pressure)

4. Hydrostatics• Pressure• HydrostaticPressureLawandItsApplications• CalculationofPressureForces

STRESSONAPOINT:3D SignConvention

STRESSONAPOINT:2D SignConvention

σy

σy

σxσx