1. Visualization of Coupled FEA, CFD and Multi-body Dynamics Simulations using EnSight Darin McKinnis Computational Engineering International (CEI) Clinton Stone MSC-Africa Simulating Reality (Pty) Ltd Paul Adams Scientific Visualization Lead ERDC MSRC - Vicksburg, MS

2. Presentation Overview
Introduction & Trends in the CAE Industry
Discussion of CAE Coupling Technologies
Post-processing Challenges
Technology Demonstrator Projects
Conclusion

4. Introduction The CAE Industry in the 1980-90’s was…
Independent CAE companies
Emerging new technologies
Maturing independent CAE disciplines (FEA, CFD, MDB, etc..)
Proprietary ‘Islands’ of technology
The CAE Industry in the new millennium is …
Integrating with CAD systems
Acquisitions, mergers, strategic alliances
Consolidation of duplicate technologies
Focus on new multi-physics technologies
Integration with other analysis disciplines
Commitment to Open standards

5. Introduction
Numerical Simulation in many respects has matured in terms of “mono-physics”
FEA, CFD, MBD, etc….
Increasing need for solution of much larger and more complex problems
Many of these problems involve the solution of “multi-physics” phenomena
Flow, Stress, Temperature, Current, Motion
Effective methods to handle “multi-physics” solutions is the core focus of much future CAE development.

6. Introduction
Many modern CAE software packages handle multi-physics to a certain degree
Thermal-Structural Coupled FEA (Temperature & Stress)
Conjugate Heat-Transfer CFD (Fluid Flow and Structure Temp)
Rigid & Flexible Body Dynamics (FEA & MBD)
Electro-Thermal-Structural (Joule Heating & Stress) …
The challenge is to solve problems involving widely varying physics, not suitable to be solved inside a single software package

7. Presentation Overview
Introduction & Trends in the CAE Industry
Discussion of CAE Coupling Technologies
Fluid Structure Interaction (FSI)
Multibody Dynamics & Finite Element Analysis (MBD / FEA)
Mesh-based parallel Code Coupling Interface (MpCCI)
Postprocessing Challenges
Technology Demonstrator Projects
Conclusion

8. Description of CAE Coupling Technology
Most CFD codes already handle basic FSI
Normally limited to Rigid body boundary motion
Mostly limited to rigid body motion by a prescribed function
Some packages include a 6DOF dynamics model to handle problems like store separation
Normally FSI requires extensive amounts of remeshing
Most FEA codes already handle basic FSI
Usually very limited in CFD ability (e.g.. Laminar Flow Only)
Usually limited to relatively small structural displacements
Primarily used to add effects of fluid mass/inertia on structural dynamics response (e.g. Seismic analysis of dams)

9. Current CFD Implementation
Moving rigid walls
with remeshing
Moving rigid walls
with overlapping meshes & 6DOF dynamics model

10. Description of certain FSI Technology
Certain codes are dedicated to handle FSI
E.g. MSC.Dytran, LS-Dyna, AutoDyn
Very capable in terms of non-linear structural dynamics
Normally limited in terms of CFD capability
Explicit codes are mainly suited to short-duration events
Normally use the ALE approach where the structure & fluid share common interface nodes
Euler mesh is “morphed” as the structure deforms
Limited to mostly relatively small displacements
Focus is usually on the structural response
Some codes have more powerful General 3D Coupling

11. General Coupling in MSC.Dytran

12. General Coupling in MSC.Dytran

13. Description of FEA/MBD Technology
Certain codes are capable of combining FEA with Multibody Dynamics (MBD)
E.g. MSC.ADAMS, LMS.Virtual.Lab, Recurdyn etc
Implementation focused on including flexibility into a rigid body dynamics system model
Flexible bodies are generated in FEA (Nastran, Ansys, Abaqus) and included as modal deformable bodies into the MDB code
These Flex bodies function only in the linear range of deflection
Implementation excludes non-linear effects like stiffening or surface contact

14. Examples of FEA/MDB Coupling

15. Examples of FEA/MDB & Aero Coupling
These simulations make use of the ability to scale the FEA based “modal loads” to apply the dynamically changing aerodynamic loads onto the flexible structure using a “look-up” table approach.
The approach ignores advanced CFD effects and interactions.

16. Description of CAE Coupling Technology
Despite the progress already made in FSI & FEA/MDB coupling, the tools are either rather limited or very specialized for specific applications
Short Duration, Airbags, explosions, bird-strike, linear flexibility…
A growing need exists to make multi-physics coupling more general and powerful
One solution is to combine the strengths of multiple CAE tools using technology such as MpCCI

17. MpCCI: Description and Motivation
Mesh-based parallel Code Coupling Interface.
Handles data communication between two or more simulation codes
Supports non-matching grids and handles data interpolation (conservative and non-conservative) between the grids.
Supports parallelization of the codes.
Includes an intuitive GUI for setup of the simulation
Developed by:
Fraunhofer Institute for Algorithms and Scientific Computing SCAI
See:

18. MpCCI: Description and Motivation

19. MpCCI: Description and Motivation
Current MpCCI Technology Partners
MSC.Software
CD-adapco
Abaqus
Ansys
Fluent
CEI (EnSight)
Others…
MpCCI Code Support (v 3.0.x)
ABAQUS (V Dec 2004) ANSYS (V Dec 2004) Fluent (V Dec 2004) StarCD (V Dec 2004) Permas (V planned April 2005) RadTherm (V planned April 2005) CFX (V planned later 2005) Marc & Nastran (V planned Q3 2005)

20. MpCCI: Basic Principles
Interaction between FEA & CFD codes takes place at a coupling interface via appropriate boundary conditions.
Both FEA and CFD will have three or five points (synchronisation points) in the code, where data may be exchanged:
SP1: Start of the analysis (increment 0).
SP2: Start of an increment.
SP3: End of an increment.
SP4: Start of an iteration.
SP5: End of an iteration.

21. MpCCI: Basic Principles
The user determines coupling algorithm by specifying:
the synchronisation points of FEA and the CFD code that communicate which each other; and
the data that must be exchanged between these communicating synchronisation points.
Weakly coupled solution requires 3 SP’s
Uses Alternating Algorithm
Strongly coupled solution requires 5 SP’s
Uses Parallel Algorithm

22. MpCCI: Architecture

23. MpCCI: Core Technology
Advanced Coupling Algorithms
Advanced Interpolation Technology

24. Internals of a Non-Linear Solution
SP1
SP2
SP4
SP3 CC
SP5
- structural
- heat transfer
- ...
increment (time step) loop
nonlinear iteration loop
start of analysis
start of increment (time step)
start of iteration
end of iteration
end of increment (time step)
CCI_Check_Convergence()

25. MpCCI: Weakly Coupled SP1 SP2 SP4 SP3 CC SP5 - structural
- heat transfer
stress
displacement …
time step loop
iteration loop
- fluid flow
velocity
pressure
fluid pressure & temperature
updated geometry

26. MpCCI: Strongly Coupled
SP1
SP2
SP4
SP3 CC
SP5
- structural
- heat transfer
stress
displacement …
time step loop
iteration loop
- fluid flow
velocity
pressure
fluid pressure
updated geometry

27. Status of MSC.Marc & MpCCI
Interface successfully used in:
DEBUT Project (Multi-Disciplinary Engineering By Using coupling Technology)
fluid-solid interaction problems in airbag gas generators
TROPHY Project (Towards Prediction of Hydroplaning: Numerical Simulation and Experimental Validation)
hydroplaning simulations

28. Other MpCCI Technology Projects
Damping of piezo elements 
StarCD–ANSYS  
Aero-elastic in aircraft design 
Flower–Nastran  
Cabin acoustic in aircraft 
ACTI3S–Nastran  
Polymer mixers 
StarCD–Permas  
Airbag gas generator simulations 
CFX–Marc  
Aquaplaning computations 
Numeca–Marc  
Vibration in pipeline systems 
Fluent–ANSYS  
Rubber gaskets 
Fluent–ANSYS/ ABAQUS  
Wind loads in civil engineering 
CFX–InHouse  
Aerodynamics in automotive design 
StarCD–Nastran/ ABAQUS  
Biomechanical simulations 
StarCD–Mecano  

29. Presentation Overview
Introduction & Trends in the CAE Industry
Discussion of CAE Coupling Technologies
Fluid Structure Interaction (FSI)
Multibody Dynamics & Finite Element Analysis (MBD / FEA)
Mesh-based parallel Code Coupling Interface (MpCCI)
Postprocessing Challenges
Technology Demonstrator Projects
Conclusion

30. Postprocessing Challenges
Any form of multi-code coupled simulation has problems in terms of results visualization
Each CAE package is designed to only postprocess its specific results
Viewing the different result domains separately significantly reduces the engineering value of the simulation
Often sequentially coupled solutions are conducted with very different time scales

31. Postprocessing Challenges
EnSight is unique in its ability to postprocess coupled simulation results.
These can either be:
Directly coupled with co-simulation or MpCCI
Sequentially coupled using tools like iSight-FD or Fiper
Manually coupled solutions using loads transfer
Decoupled simulations of separate physics portions of a problem
Ensight features required for this are:
Multi-code readers
Results Timeline manipulation
Keyframing & Viewport Tracking
Multiple Case Support
Case Mapping (Pressure from CFD to FEA)
Global model repositioning (Frame Mode)

32. Presentation Overview
Introduction & Trends in the CAE Industry
Discussion of CAE Coupling Technologies
Fluid Structure Interaction (FSI)
Multibody Dynamics & Finite Element Analysis (MBD / FEA)
Mesh-based parallel Code Coupling Interface (MpCCI)
Postprocessing Challenges
Technology Demonstrator Projects
Conclusion

33. Technology Demonstrators
The following examples will illustrate the use of EnSight to postprocess coupled simulations
These examples highlight all of the methods previously discussed for coupling

34. Technology Demonstrators
Helicopter Crash Investigation
Sequentially Coupled MBD & FEA simulation

35. Technology Demonstrators
Pickup Truck Crash Investigation
Sequentially Coupled MBD & FEA simulation

36. Technology Demonstrators
Aircraft flap & air-brake deployment
Sequentially Coupled MBD & CFD simulation

37. Technology Demonstrators
Aircraft flap & air-brake deployment
Sequentially Coupled MBD & CFD simulation

38. Technology Demonstrators
Automotive Manifold
Coupled CFD & FEA simulation using MpCCI

39. Technology Demonstrators
Flexible Membrane Flutter
Coupled CFD & FEA simulation using MpCCI

40. Technology Demonstrators
Biomedical Heart-Valve
Coupled CFD & FEA simulation using MpCCI

41. Technology Demonstrators
Bi-Metallic Strip Flow Restrictor
Coupled CFD & FEA simulation using MpCCI

42. Technology Demonstrators
Dragline Dynamics & Digging
MSC.Dytran solves to system / soil interaction
MSC.ADAMS solves the dynamics of the system
Co-Simulation coupling with MBD & CFD simulation

43. Technology Demonstrators
Bungee Jumper
Co-Simulation coupling with MBD & Non-linear FEA

44. Technology Demonstrators
Sloshing Tank Test rig
Co-Simulation coupling with MBD & CFD

45. Technology Demonstrators - Povray !
Sloshing Tank Test rig
Pov-ray now available in EnSIght Standard, no longer requires EnSight Gold (2013)
Co-Simulation coupling with MBD & CFD

46. Technology Demonstrators - Povray !
Flow around bridge footing
Flow simulation vs experimental results

47. Conclusion
The future of Computer Aided Engineering will lie in solving more complex multi-physics problems.
CAE companies are increasing focus on solver integration and cross-discipline coupling
CEI is leading the way in the postprocessing requirements for the future of CAE coupled simulations.

48. Thank you….