December 2003 3rd FENET Annual Industry Meeting Slide 1
Simulation of Fluid-Structure Interactions in Aeronautical Applications
Martin KuntzJorge Carregal FerreiraANSYS GermanyD-83624 [email protected]
December 2003 3rd FENET Annual Industry Meeting Slide 2
Outline
• Flow Analysis with CFX-5.6– Numerical scheme– Turbulence modeling– Applications
• Structural Analysis with ANSYS– Applications
• Fluid-Structure Interaction with ANSYS / CFX– Multiphysics – Applications
December 2003 3rd FENET Annual Industry Meeting Slide 3
ANSYS Organisation
ANSYS, Inc.
FluidsMeshingMechanical
CoreTechnologies
CFXICEM-CFDANSYS
IntegrationPlatform ANSYS Workbench
BusinessUnits
December 2003 3rd FENET Annual Industry Meeting Slide 4
CFX-5 Numerical Method
• Finite volume method for hybrid grids
• Conservative, vertex-based discretization• Implicitly coupling of equations• Rhie/Chow pressure-velocity coupling• Algebraic multigrid• Scalable parallelization• Second order space and time discretization• Suitable for whole range of Mach- and Reynolds
numbers
December 2003 3rd FENET Annual Industry Meeting Slide 5
CFX-5 Turbulence Modelingk-ε model
SST model
k-ε model
SST model
• Variety of models– For different types of flow– With different
computational effort• Examples
– One-equation models (KE1E)
– Two-equation models (SST, k-eps)
– Reynolds stress models (LLR, SSG)
– DES / LES models
December 2003 3rd FENET Annual Industry Meeting Slide 6
NACA 4412 Airfoil
December 2003 3rd FENET Annual Industry Meeting Slide 7
Shear-Stress Transport Model
• Optimized model for flow with separation and adverse pressure gradients
• Zonal model– k-omega model near the wall– k-epsilon model in freestream
• Blending dependent on solution• Additional limiter for turbulent viscosity • Automatic blending between• Wall treatment
– Logarithmic law on coarse grids– Low-Re formulation on fine grids
December 2003 3rd FENET Annual Industry Meeting Slide 8
Aerodynamic Applications
• DLR F6 Wing/Body/Nacelle/Pylon configuration– Particpation at AIAA drag prediction workshop 2003,
Orlando– Analysis of accuracy and performance of CFD codes – Participants
• Industry: Airbus, Boeing, CESNA• Research centers: NASA; DLR, ONERA, NAL, QinetiQ• Universities
• Two Configurations• Wing / body• Wing / body/
nacelle / pylon
December 2003 3rd FENET Annual Industry Meeting Slide 9
DLR F6: Lift for Wing Body
• Wing / body Configuration– Medium grid– 5.8 million nodes– ICEM-Hexa
• Excellent agreement for complete range of incident
Angle of Attack [Deg]
Lift
Coe
ffici
ent
December 2003 3rd FENET Annual Industry Meeting Slide 10
DLR F6: Turbulence Model
NASA Codes CFX 5
CL increased by 0.015 when SST A1 changed from 0.31 to 0.33 (Reduced separation, comparable to S-A turbulence model)
⎥⎦
⎤⎢⎣
⎡Ω
=2
1* ;minF
kakt
ρωραµ
CL increased by 0.015 when SST A1 changed from 0.31 to 0.33 (Reduced separation, comparable to S-A turbulence model)
⎥⎦
⎤⎢⎣
⎡Ω
=2
1* ;minF
kakt
ρωραµ
December 2003 3rd FENET Annual Industry Meeting Slide 11
DLR F6: Lift vs. Drag
CFX-5
• Design parameter drag• Good agreement with SST model• Constant deviation for Spalart-Almaras model
Lift
Coe
ffici
ent
Drag CoefficientDrag Coefficient
December 2003 3rd FENET Annual Industry Meeting Slide 12
Computational Performance
• Lift and Drag converged after 120 iterations
• Oscillations in residuals due to transient separation
• Computation time about 12h fort 6 M nodes on 16 processors
December 2003 3rd FENET Annual Industry Meeting Slide 13
Structural Analysis
• Initial focus on analysis of solids– Structural
analysis, thermal analysis
• Expanding focus to other fields– Multiphysics
environment
Structural
Fluid
Thermal
Electrostatic
Electrical
Magnetic
HFEMAG
December 2003 3rd FENET Annual Industry Meeting Slide 14
Strategy: Multiphysics
HeatHeatTransferTransfer
SolidSolidMechanicsMechanics
MagnetismMagnetismFluidFluidMechanicsMechanics
ElectricityElectricity
ANSYS MultiPhysics
December 2003 3rd FENET Annual Industry Meeting Slide 15
Fluid-Structure Interaction
• Simultaneous run of individual software – Using advanced and
validated features of participating codes
– Exchanging data at common boundaries or overlapping domains
• Simultaneous solution of multiple fields in single solver– Non-optimal software
for individual fields– Requirement for
common grid– Large problems
become computationally expensive
⇒ ANSYS / CFX code coupling
December 2003 3rd FENET Annual Industry Meeting Slide 16
FSI Classification
CFD
Thermal
Structural
ElectromagneticsMultiphysics
One-way Two-way
Explicit ImplicitIterativeCoupling algorithm
VolumeSurfaceInteraction domain
Heat flux Heat source
Mom. source
Pressure Force
Temperature
Velocity
Displacement
Exchange variables
Files MPITransfer medium
December 2003 3rd FENET Annual Industry Meeting Slide 17
Two-way Coupling
Coef. loop
FSITimeloop
Stagger loop
FSITimeloop
CFX-5solver
ANSYSsolver
December 2003 3rd FENET Annual Industry Meeting Slide 18
Interaction Domain
• Surface coupling at 2D interface
• Volume coupling at 3D domain
Fluid Solid
StructureElectro-
magneticsFluid
December 2003 3rd FENET Annual Industry Meeting Slide 19
Data Transfer
• Variables – Variables available in both fields
• Transformation– System of units, scaling
• Interpolation– Dissimilar meshes
• Data transfer media– Files, MpCCI
December 2003 3rd FENET Annual Industry Meeting Slide 20
FSI Examples
• Gas turbine• Heart valve• Aerofoil flutter
December 2003 3rd FENET Annual Industry Meeting Slide 21
FSI Application: Gas Turbine
• Gas turbine rotor: 113 blades• Interaction: Structural / thermal / fluid• CFX
– Fluid flow and CHT in blades• ANSYS
– Directly coupled elements – Thermal and structural analysis of blades
December 2003 3rd FENET Annual Industry Meeting Slide 22
Turbine: CFD
Pressure
Streamlines
Temperature
December 2003 3rd FENET Annual Industry Meeting Slide 23
Turbine: Thermal/Mechanical
Displacement
Equivalent stress (SEQV)
Temperature
December 2003 3rd FENET Annual Industry Meeting Slide 24
St Jude Heart Valve
• Popular bi-leaflet design• Coupling CFX-5 and Dynamic Rigid Body
Module• Several re-meshing steps
December 2003 3rd FENET Annual Industry Meeting Slide 25
St Jude Heart Valve
Static Result Animation
December 2003 3rd FENET Annual Industry Meeting Slide 26
St Jude Validation
• Valve Angle against time
December 2003 3rd FENET Annual Industry Meeting Slide 27
Wing Flutter
• AGARD 445.6 testcase• Experimental set-up
described in AGARD Report 765
• Wall-mounted semispanmodel, mahogany
• Wing aspect ratio: 1.6525, quarter-chord sweepback angle 45 deg.
December 2003 3rd FENET Annual Industry Meeting Slide 28
Wing Flutter
• Test case : Mach number 0.901• CFD grid: 272.600 nodes, CSA grid: 960 nodes• Grid generation ICEM-HEXA
December 2003 3rd FENET Annual Industry Meeting Slide 29
Summary
• Fluid Structure Interaction software for aerodynamic applications– Accurate prediction of flow field and global
parameters– High performance – Efficient coupling algorithms
• Future– Continuation of validation work– Improvement of usability
