PARTICLE-IN-CELL METHODS PRESERVING SHEARING AND ROTATION

Number: 20170185701
Published: 2017-06-29
Filed: 2015-12-28
Assignee: Disney Enterprises, Inc.
Inventors: STOMAKHIN; Alexey, TERAN; Joseph
CPC: G06F30/20; G06F17/10
Verdict: Medium Notable software
Source: Google Patents · FreePatentsOnline

The keeper's note

A rigid particle-in-cell simulation method that reduces information loss when transferring data between particles and grid in hybrid physics simulations (e.g. snow, sand VFX).

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

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited aspects are attained and can be understood in detail, a more particular description of aspects of this disclosure, briefly summarized above, may behad by reference to the appended drawings.

It is to be noted, however, that the appended drawings illustrate only typical aspects and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective aspects.

FIG. 1 illustrates an approach for simulating a system, according to an aspect of this disclosure.

FIG. 2 illustrates an example of a simulation using a particle-in-cell method preserving shearing and rotation compared to traditional techniques, according to an aspect of this disclosure.

FIG. 3 illustrates a second example of a simulation using the particle-in-cell method preserving shearing and rotation compared to traditional techniques, according to an aspect of this disclosure.

FIG. 4 illustrates a third example of a simulation using the particle-in-cell method preserving shearing and rotation comparedto traditional techniques, according to an aspect of this disclosure.

FIG. 5 illustrates a method for simulating a system, according to an aspect of this disclosure.

FIG. 6 illustrates a computer system in which an aspect of this disclosure may be implemented.

To facilitate understanding, identical reference numerals have been used, where possibl

Claims

1. A computer-implemented method of simulating a system, comprising, 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, wherein the transfer from the particles to thegrid and the transfer back from the grid to the particles act as filters and conserve angular momentum. 10. A non-transitory computer-readable storage medium storing a program, which, when executed by a processor performs operations for simulating a system, the operations comprising, 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, 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. 19. A system, comprising: a processor; and a memory, wherein the memory includes a program configured to perform operations for simulating a system, the operations comprising, for one or more iterations: transferring system information including angular momentum information from particles to agrid 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 particlesto the grid and the transfer back from the grid to the particles act as filters and conserve angular momentum.