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IMPETUS AFEA | SOLVER® 1
GTC May 2012
Fluid-Structure-Interaction Using SPH and GPGPU Technology
IMPETUS AFEA | SOLVER®
Jérôme Limido
Jean Luc Lacome
Wayne L. Mindle
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IMPETUS AFEA | SOLVER® 2
2D Sloshing Water in Tank
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IMPETUS AFEA | SOLVER® 3
History
Development started in 2007
Languages
Fortran
Cuda
C++
Structure Source Code % of Lines
Finite Element 40%
Smoothed Particles 10%
Discrete Particles 10%
GPU computing 25%
Misc(output,util,lic) 15%
Number of lines of code: 110,000
IMPETUS Afea | SOLVER ®
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IMPETUS AFEA | SOLVER® 4
Particle methods are very well suited for the GPU
- All particle methods run on the GPU
- Peak acceleration can reach 100x on simple (non industrial) cases
Finite element method is more complex to port to the GPU - Most time consuming parts are treated on GPU
- Classic FEM could be easier to port on GPU
Contact algorithm is very complex to optimize on the GPU - Balance between computation time and uniqueness of contact definition
- Current state : 50% CPU time spent in contact algorithm
Porting to GPU
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Meshless Methods : GPU vs CPU
Sort – Neighbor list Particle Interaction System update
0.0% 50.0% 100.0%
Sort
Entities Interaction
System Update
Sort Entities Interaction System Update
GPU 6% 92.5% 1.5%
CPU 0.7% 99% 0.3%
System Update
Particle Interaction
Sorting
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IMPETUS AFEA | SOLVER® 6
Gas
High Explosives
Soil
Fluids
DP (Discrete Particles)
SPH (Smoothed-Particle Hydrodynamics)
Particle Methods
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Kinetic molecular theory for gases (modified to handle high explosives)
Discrete grains in contact. Grain size distribution, friction, damping and contact stiffness are adapted to match a given EOS.
DP (Discrete Particles)
Buried Mine Blast
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IMPETUS AFEA | SOLVER® 8
4M Sand Particles
60K HE Particles
Run Time: 1 hour
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DP (Discrete Particles)
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IMPETUS AFEA | SOLVER® 9
t = 0 t = 0.1ms t = 0.2ms
Penetration of a Sand Filled Profile
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DP (Discrete Particles)
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IMPETUS AFEA | SOLVER® 10
• Unique SPH formulation
• Compute accurate and stable pressure fields
• Multi-fluid applications
• Air, Water and Gas
• Efficient SPH to Finite Element contact algorithm
SPH (Smoothed-Particle Hydrodynamics)
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IMPETUS AFEA | SOLVER® 11 11
Hydraulic RAM – Projectile Impacting a fluid filled structure
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Hydraulic RAM – Projectile Impacting a fluid filled structure
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Hydraulic RAM – Projectile Impacting a fluid filled structure
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IMPETUS AFEA | SOLVER® 14
DAM Break Run Time: 1 hour
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Run Time: 1 hour DAM Break
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IMPETUS AFEA | SOLVER® 16
Water Filled Balloon
Half filled Balloon Dropped followed by Base Excitation
848,947 SPH Particles
Run Time: 24.7 hours
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IMPETUS AFEA | SOLVER® 17
Water Filled Balloon
Half filled Balloon Dropped followed by Base Excitation
848,947 SPH Particles
Run Time: 24.7 hours
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IMPETUS AFEA | SOLVER® 18
Heart Valve 468,931 SPH Particles
Run Time: 12.5 hours
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IMPETUS AFEA | SOLVER® 19
Heart Valve
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Heart Valve
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IMPETUS AFEA | SOLVER® 21
Speed up allows development of new algorithms to solve
more complex problems and still provide an accurate solution.
Speed up is a way to increase the model size and still provide
an accurate solution.
What does increased speed mean?
Performance of Real World Problems
Full scale blast simulation (Discrete Particles + FE) : ~10x
Full scale FSI simulation (SPH + FE) : ~ 40x
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IMPETUS AFEA | SOLVER® 22
Development Goals
• Accuracy
• Robust Algorithms
• Simplified Input
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GPU Technology
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Accurate and Robust
Unique accurate higher order solid elements that can handle extremely
large deformations (good for plasticity and bending, fully integrated, no
hourglassing and no element inversion).
Cubic 64-node hexahedron Cubic 20-node
Tetrahedron
Cubic 40-node
Pentahedron
Linear and Quadric: Hex, Tet and Penta Elements too.
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IMPETUS AFEA | SOLVER® 25
• Unique higher order element technology is well suited for processes involving extreme
deformations.
• Elements are accurate, even at large aspect ratios, and they behave well in dynamics.
Accurate and Robust
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IMPETUS AFEA | SOLVER® 26
Performance
Standard Explicit Dynamic FE Codes
Solid Elements based upon 1 point integration
1. Because Higher Order elements are too computational intensive
2. Require At least 3 elements through the thickness to get good
bending behavior
3. Require Hourglass Control (artificial stiffness) to numerically stabilize
the elements
IMPETUS AFEA Solver
Good performance because of GPU
Technology
Up to 64 integration points per solid element
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Methods and Algorithms
Designed with as few numerical parameters to tune as possible.
User Input is kept to a Minimum:
• Material models
• Contact Definition
• Failure Criteria
What Does this means to the Analyst?
More time to focus on the physics of the problem instead of troubleshooting input data.
Simplified Input
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IMPETUS AFEA | SOLVER® 28
Demands on Simulation Software:
Larger and Larger Models multiple GPUs
• Visualization
• Complex mixing, phase transition multi-phasic
• Composites: crash and impact multi-scale approach
Future Development
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