1. Interesting papers on SIGGRAPH 2005 Korea University Computer Graphics Lab. Jin-Kyung Hong

2. A Vortex Particle Method for Smoke, Water and Explosions Andres Sell (Stanford University and Intel Corporation) Nick Rasmussen (Industrial Light & Magic) Ron Fedkiw (Stanford University and Industrial Light & Magic)

3. 3 Summary Keywords –Vortex methods, fluids, smoke, water, explosions Highly turbulent effects –Grid based method Uniform or octree grid –Vortex particle method Eliminate dissipation, Increase details –Vorticity forcing Grid based velocity field towards the desired vorticity

4. 4 Results (1/2) Turbulence in water flowing (320x128x320)

5. 5 Results (2/2) Smoke explosion (180x260x180)

6. Animating Gases with Hybrid Meshes Bryan E. Feldman James F. O’Brien Bryan M. Klingner (University of California, Berkeley)

7. 7 Overview (1/2) Keywords –Natural phenomena, physically based animation, CFD

8. 8 Overview (2/2) Animating gases –on unstructured tetrahedral meshes –the interaction of the fluids with irregularly shaped obstacles Hybrid mesh –Combine tetrahedral cells with regular hexahedral cells Naturally suited to behavior at curved or angled boundaries –Accuracy near obstacles –Efficiency in open regions

9. 9 Method (1/2) Discretization –Regular grids smoothly joined to irregular tetrahedral

10. 10 Method (2/2) Accelerations due to Body Forces –Gravity, vorticity confinement Semi-Lagrangian integration Mass Conservation –Open boundary, closed boundary Interpolation –Regular hexahedral cells –Tetrahedral and transition cells

11. 11 Results

12. Animating Sand as a Fluid Yongning Zhu Robert Bridson

13. 13 Summary Keywords –Sand, water, animation, physical simulation Existing fluid solver  granular materials Sand modeling –Friction Fluid simulation Surface reconstruction from particles

14. 14 Results (1/3) As water and as sand (100x100x100)

15. 15 Results (2/3) Compare to previous one –Friction coefficient between the sand and other objects e.g. solid wall boundaries

16. 16 FLIP vs. PIC FLIP: Fluid Implicit-Particle –Small-scale velocities preserved –Inviscid flows, water PIC: Particle-in-Cell –Smoothed away –Viscous flows, sand

17. 17 Results (3/3) Granular material (100x60x60)