Fluid-Structure-Interaction Using SPH and GPGPU Technology

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1 IMPETUS AFEA SOLVER Fluid-Structure-Interaction Using SPH and GPGPU Technology Jérôme Limido Jean Luc Lacome Wayne L. Mindle GTC May 2012 IMPETUS AFEA SOLVER 1

2 2D Sloshing Water in Tank IMPETUS AFEA SOLVER 2

3 IMPETUS Afea SOLVER 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 3

4 Porting to GPU 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 IMPETUS AFEA SOLVER 4

5 Meshless Methods : GPU vs CPU Sort Neighbor list Particle Interaction System update System Update System Update Particle Interaction Entities Interaction Sorting Sort 0.0% 50.0% 100.0% Sort Entities Interaction System Update GPU 6% 92.5% 1.5% CPU 0.7% 99% 0.3% IMPETUS AFEA SOLVER 5

6 Particle Methods Gas High Explosives Soil Fluids DP (Discrete Particles) SPH (Smoothed-Particle Hydrodynamics) IMPETUS AFEA SOLVER 6

7 DP (Discrete Particles) Buried Mine Blast Discrete grains in contact. Grain size distribution, friction, damping and contact stiffness are adapted to match a given EOS. Kinetic molecular theory for gases (modified to handle high explosives) IMPETUS AFEA SOLVER 7

8 DP (Discrete Particles) 4M Sand Particles 60K HE Particles Run Time: 1 hour IMPETUS AFEA SOLVER 8

9 DP (Discrete Particles) Penetration of a Sand Filled Profile t = 0 t = 0.1ms t = 0.2ms IMPETUS AFEA SOLVER 9

10 SPH (Smoothed-Particle Hydrodynamics) Unique SPH formulation Compute accurate and stable pressure fields Multi-fluid applications Air, Water and Gas Efficient SPH to Finite Element contact algorithm IMPETUS AFEA SOLVER 10

11 Hydraulic RAM Projectile Impacting a fluid filled structure IMPETUS AFEA SOLVER 11

12 Hydraulic RAM Projectile Impacting a fluid filled structure IMPETUS AFEA SOLVER 12

13 Hydraulic RAM Projectile Impacting a fluid filled structure IMPETUS AFEA SOLVER 13

14 DAM Break Run Time: 1 hour IMPETUS AFEA SOLVER 14

15 DAM Break Run Time: 1 hour IMPETUS AFEA SOLVER 15

16 Water Filled Balloon 848,947 SPH Particles Run Time: 24.7 hours Half filled Balloon Dropped followed by Base Excitation IMPETUS AFEA SOLVER 16

17 Water Filled Balloon 848,947 SPH Particles Run Time: 24.7 hours Half filled Balloon Dropped followed by Base Excitation IMPETUS AFEA SOLVER 17

18 Heart Valve 468,931 SPH Particles Run Time: 12.5 hours IMPETUS AFEA SOLVER 18

19 Heart Valve IMPETUS AFEA SOLVER 19

20 Heart Valve IMPETUS AFEA SOLVER 20

21 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 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. IMPETUS AFEA SOLVER 21

22 Development Goals Accuracy Robust Algorithms Simplified Input IMPETUS AFEA SOLVER 22

23 GPU Technology IMPETUS AFEA SOLVER 23

24 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. IMPETUS AFEA SOLVER 24

25 Accurate and Robust 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. IMPETUS AFEA SOLVER 25

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 IMPETUS AFEA SOLVER 26

27 Methods and Algorithms Designed with as few numerical parameters to tune as possible. User Input is kept to a Minimum: Simplified Input 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. IMPETUS AFEA SOLVER 27

28 Future Development Demands on Simulation Software: Larger and Larger Models multiple GPUs Visualization Complex mixing, phase transition multi-phasic Composites: crash and impact multi-scale approach IMPETUS AFEA SOLVER 28

29 Contact Info Website: IMPETUS AFEA SOLVER 29