- Number
- 10503845
- Published
- 2019-12-10
- Filed
- 2015-12-28
- Assignee
- Disney Enterprises, Inc.
- Inventors
- Stomakhin; Alexey, Teran; Joseph
- CPC
- G06F17/10; G06F30/20
- Verdict
- Low Notable software
- Source
- Google Patents · FreePatentsOnline
The keeper's note
Particle-in-cell physics simulation method.
Abstract
The disclosure provides an approach for reducing information loss when transferring from particles to grid and vice versa in a hybrid Lagrangian/Eulerian simulation, while also preserving stability. In one aspect, referred to as the rigid particle-in-cell (RPIC) method, a simulation application stores a sampling of local angular momentum for each particle, helping to preserve the angular momentum that would otherwise be lost in the transfer from grid to particles. In another aspect that is more generally applicable and referred to herein as the rigid and shearing particle-in-cell (RSPIC) method, the simulation application stores, for each particle, a matrix with rotational and shearing information. The RSPIC method effectively reduces dissipation, preserves angular momentum exactly, and prevents instabilities. Further, the RSPIC method is applicable to both incompressible liquids and material point method (MPM) simulations of materials such as solids.
Background
BACKGROUND(1) Field of the Invention(2) This disclosure provides techniques for computer simulation and rendering of phenomena. More specifically, one aspect of this disclosure presents particle-in-cell methods for the computer simulation and rendering that preserve shearing and rotation.(3) Description of the Related Art(4) Hybrid Lagrangian/Eulerian methods, in which particle and grid formulations are used in conjunction to simulate fluids and other materials undergoing large deformation, are commonplace in computer graphics simulations. However, traditional hybrid Lagriangian/Eulerian methods suffer from inherent and well-known limitations, such as unwanted dissipation of angular momentum, or noisiness and instability.SUMMARY(5) One aspect of this disclosure provides a computer-implemented method of simulating a system. The method generally includes, for one or more iterations: transferring system information including angular momentum information from particles to a grid on which dynamics are computed, and transferring the system information including the angular momentum information and velocity information back from the grid to the particles on which at least velocity changes are computed, where the transfer from the particles to the grid and the transfer back from the grid to the particles act as filters and conserve angular momentum. In another aspect, the system information that is transferred from the particles to the grid and back from the grid to the particles fur
Claims
1. A computer-implemented method of simulating and rendering a visual depiction of a system, comprising: simulating the system, wherein the system includes at least one material, and wherein simulating the system comprises, for each of one or more iterations: transferring system information including angular momentum information from particles to a grid on which dynamics are computed, and transferring the system information including the angular momentum information and velocity information back from the grid to the particles on which at least velocity changes are computed, wherein the transfer from the particles to the grid and the transfer back from the grid to the particles act as filters and conserve angular momentum; and rendering for display one or more images depicting the system including the at least one material based, at least in part, on the simulation of the system.
2. The method of claim 1, wherein: the system information that is transferred from the particles to the grid and back from the grid to the particles further includes shearing information; and the transfer from the particles to the grid and the transfer back from the grid to the particles also preserve shearing modes.
3. The method of claim 2, wherein: the dynamics computed on the grid include at least one of forces, collision responses, and incompressible projections; at least the velocity changes and angular momentum changes are computed on the particles; and the particles are advected.
4. The method of claim 2, wherein the angular momentum and the shearing information are stored in a matrix.
5. The method of claim 2, wherein: the system includes a fluid; and the system information is transferred from the particles to marker-and-cell (MAC) faces of the grid.
6. The method of claim 2, wherein: the system includes a solid; and the one or more iterations are iterations in a material-point-method (MPM) loop.
7. The method of claim 2, further comprising, blending the simulation of the system with a particle-in-cell (PIC) simulation technique.
8. The method of claim 2, wherein: the system includes a plurality of materials; and the simulation is a coupled simulation of the plurality of materials.
9. The method of claim 2, wherein the dynamics computed on the grid include mesh-based Lagrangian forces.
10. A non-transitory computer-readable storage medium storing a program, which, when executed by a processor performs operations for simulating and rendering a visual depiction of a system, the operations comprising: simulating the system, wherein the system includes at least one material, and wherein simulating the system comprises, for each of one or more iterations: transferring system information including angular momentum information from particles to a grid on which dynamics are computed, and transferring the system information including the angular momentum information and velocity information back from the grid to the particles on which at least velocity changes are computed, wherein the transfer from the particles to the grid and the transfer back from the grid to the particles act as filters and conserve angular momentum; and rendering for display one or more images depicting the system including the at least one material based, at least in part, on the simulation of the system.
11. The computer-readable storage medium of claim 10, wherein: the system information that is transferred from the particles to the grid and back from the grid to the particles further includes shearing information; and the transfer from the particles to the grid and the transfer back from the grid to the particles also preserve shearing modes.
12. The computer-readable storage medium of claim 11, wherein: the dynamics computed on the grid include at least one of forces, collision responses, and incompressible projections; at least the velocity changes and angular momentum changes are computed on the particles; and the particles are advected.
13. The computer-readable storage medium of claim 11, wherein the angular momentum and the shearing information are stored in a matrix.
14. The computer-readable storage medium of claim 11, wherein: the system includes a fluid; and the system information is transferred from the particles to marker-and-cell (MAC) faces of the grid.
15. The computer-readable storage medium of claim 11, wherein: the system includes a solid; and the one or more iterations are iterations in a material-point-method (MPM) loop.
16. The computer-readable storage medium of claim 11, the operations further comprising, blending the simulation of the system with a particle-in-cell (PIC) simulation technique.
17. The computer-readable storage medium of claim 11, wherein: the system includes a plurality of materials; and the simulation is a coupled simulation of the plurality of materials.
18. The computer-readable storage medium of claim 11, wherein the dynamics computed on the grid include mesh-based Lagrangian forces.
19. A system, comprising: a processor; and a memory, wherein the memory includes a program configured to perform operations for simulating and rendering a visual depiction of a system, the operations comprising: simulating the system, wherein the system includes at least one material, and wherein simulating the system comprises, for each of one or more iterations: transferring system information including angular momentum information from particles to a grid on which dynamics are computed; and transferring the system information including the angular momentum information and velocity information back from the grid to the particles on which at least velocity changes are computed, wherein the transfer from the particles to the grid and the transfer back from the grid to the particles act as filters and conserve angular momentum, and rendering for display one or more images depicting the system including the at least one material based, at least in part, on the simulation of the system.
20. The system of claim 19, wherein: the system information that is transferred from the particles to the grid and back from the grid to the particles further includes shearing information; and the transfer from the particles to the grid and the transfer back from the grid to the particles also preserve shearing modes.