ACUSIM Software Inc., 2685 Marine Way, Suite 1421, Mountain View, California 94043Tel: (650) 988-9700 Fax: (650) 988-9770 [email protected] http://www.acusim.com
Coupling AcuSolve with
MD-Nastran:
Fluid Structure Interaction
Acusim Software Inc. Proprietary Information
Farzin Shakib April 21, 2009
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Outline
Product Overview
Fluid Structure Interaction (FSI)Practical FSI: Linear Solid/Structural Analysis
Direct-Coupling FSI: Nonlinear Solid/Structural Analysis
Advance FSI Features
Conclusion
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Product Overview
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AcuSolve
A powerful general-purpose finite element flow solver
AcuSolve’s differentiation:Robustness Most problems solved on the first attemptSpeed Coupled solver on distributed parallel machinesAccuracy Highly accurate in space and time while
globally and locally conservativeFeatures Rich set of functionality; continuously growing
An ideal enabling technology for integrated engineering and scientific applications
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Main Features
Physics:Incompressible & weakly compressible Navier-StokesThermal analysis
Conjugate heat transferMulti-layered thermal shellEnclosure radiation – View factorsSolar radiation
Multi-species transport equationsTurbulence:
One-equation Spalart-Allmaras RANS modelSmagorinsky and dynamic subgrid LES modelsHybrid RANS/LES (DES) model & (DDES)
Time accurate transient simulationCoupled with control systems
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Main Features (cont)
Arbitrary Eulerian Lagrangian FormulationFlexible mesh motionFree surfaceGuide surfaceSliding mesh
Fluid/Structure InteractionsPractical FSI (P-FSI)Direct Coupling FSI (DC-FSI)Rigid body & flow coupling
Support for ComputationalAero Acoustics (CAA) simulationsGUI-based Preprocessor
Auto tet mesher with boundary layerCAE automation
and many more …
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AcuConsole
GUI-base preprocessor for AcuSolveStarts from CAD or MESH
ProE, Parasolid, ACIS, Catia V5, DiscreteICEM, Harpoon, Hypermesh, GridGen, …
Generate mesh from CADAutomatic tet mesherBoundary layer
Full problem specificationGlobal parametersBoundary conditions, etc.
Launch solverMonitor progress
Customizable for easy deployment
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Fluid Structure Interaction
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FSI Technology
Practical FSIModal response of solid/structure given to AcuSolveAcuSolve runs by itself
Fast, easy and robustAccommodates linear solid/structure interactions
Released Q2-2004
Direct-Coupling FSITight coupling of AcuSolve & Solid/Structural Code
Two codes run in tandem Projection & interpolation performed by AcuSolveNo intervening middleware
Released Q2-2007Soon to be released with MD-Nastran OpenFSI
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Practical FSI: Linear Solid/Structural Analysis
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Practical FSI
Step 1: Solid ModelSolve an Eigenvalue problem using Nastran
Step 2: ProjectionProject the Eigenvectors onto the AcuSolve mesh
Built-in tools to extract and project directly from OP2 files
Step 3: Run AcuSolveSolve the transient coupled flow and linear deformationAt each step, AcuSolve
Computes fluid forces on the wet surfaceProjects the forces onto the EigensystemAdvances the modal responseComputes the new mesh positionSolves the fluid and other equations on the deformed mesh
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Advantages & Limitations
Advantages:The fluid and solid codes are run independently and separately
No run time coupling is requiredNo fluid mesh size limitation imposed by FSI
Significantly more stable than alternative approachesEliminates high wave number modes, yields smooth coupling
Very efficientProblem setupCPU time
Limitations:Only linear solid/structural analysis
No material or geometric nonlinearitiesOnly simple contacts
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Wind Turbine Modeling
National Renewable Energy Laboratory (NREL) modelTransient Sliding Mesh Model - Flexible Blades
Total of 20 structural modes were included for this analysis.
Wind Turbine
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Direct-Coupling FSI:Nonlinear Solid/Structural Analysis
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Direct-Coupling FSI
Step 1: MD-Nastran input fileSetup an independent solid/structural mesh and input file
Identify the solid wet surface
Step 2: AcuSolve input fileSetup an independent fluid mesh and input file
Identify the fluid wet surface
Step 3: Run AcuSolve and MD-NastranStart MD-Nastran
SCA Library & Resource Catalog set for OpenFSI/AcuSolveStart AcuSolve
Given host name of running MD-NastranMay run in parallel
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Direct-Coupling FSI (cont)
At the start of runMD-Nastran via SCA sends its surface definition to AcuSolveAcuSolve builds interpolation and projection data structure
At each time stepsAcuSolve and MD-Nastran exchange nodal forces and displacement on solid wet surface
Solid Large Deformation Equations
ALE Mesh Motion
Fluid Equations of Motion
Fluid Forces (Traction) Projectedon Solid Wet Surface
Displacement on SolidWet Surface
Deformed Fluid Mesh & Mesh Velocity on Fluid Wet Surface
AcuSolve
MD-Nastran
Vertical Baffle
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First coupling solution of AcuSolve and MD-NastranExplicit OpenFsi
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Conclusions
AcuSolve is a powerful general purpose CFD codeThe premier commercial finite element based CFD solver
AcuSolve has two FSI capabilitiesPractical FSI
Simple to set up and runVery robustOnly linear structural response
Direct-Coupling FSISimple to set up and runFull nonlinear structural response
Stable for a wide-range of problems
Both FSI options are well integrated with MD-Nastran