# US 11,113,438 B2 · Fluid simulation program, fluid simulation method, and fluid simulation device

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- Number: US 11,113,438 B2
- Document ID: US11113438B2
- Status: Granted
- Kind: B2
- Application number: 16/151,447
- Filed: 2018-10-04
- Published: 2019-04-11
- Granted: 2021-09-07
- Earliest claimed: 2017-10-10
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Tamon Suwa; Masaki Kazama
- Web page: https://patentgrep.com/patent/US11113438B2

## CPC

- G06F 30/28: using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
- G06F 30/20: Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30)
- G06F 30/23: using finite element methods [FEM] or finite difference methods [FDM]
- G06F 30/25: using particle-based methods
- G06T 13/60: of natural phenomena, e.g. rain, snow, water or plants
- G06T 15/08: Volume rendering
- G06F 2111/10: Numerical modelling
- G06T 2210/24: Fluid dynamics
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A fluid simulating method includes extracting, based on positional information included in particle data of particles during a predetermined time period, a first particle with a predetermined value or less of distance from a fluid particle and a second particle with the predetermined value or less of distance from the first particle from among wall boundary particles related to a boundary with a wall. The method may also include setting a boundary condition of a pressure Poisson equation for calculating pressure to be applied to each of the particles, and calculating pressure to be applied to each of the particles, based on the extracted first particle and the extracted second particle. The method may also include calculating particle data of the particles during a next time period based on the calculated pressure.

## Claims

### Claim 1

A non-transitory computer-readable storage medium storing a fluid simulating program for causing a computer to execute a process, the process comprising:
extracting, based on positional information included in particle data of particles, including fluid particles and wall boundary particles related to a boundary with a wall, during a predetermined time period, a first particle from among the wall boundary particles with a predetermined value or less of distance from a fluid particle among the fluid particles and a second particle with the predetermined value or less of distance from the first particle from among the wall boundary particles excepting the first particle;
setting a boundary condition of a pressure Poisson equation for calculating pressure to be applied to each of the particles;
calculating the pressure to be applied to each of the particles, based on the first particle and the second particle; and
calculating the particle data of the particles during a next time period based on the pressure,
the boundary condition includes that the first particle is set to a fixed fluid particle whose velocity is a predetermined value and that pressure to be applied to the second particle is 0.

### Claim 2

A fluid simulating method performed by a computer, the method comprising:
extracting, based on positional information included in particle data of particles, including fluid particles and wall boundary particles related to a boundary with a wall, during a predetermined time period, a first particle from among the wall boundary particles with a predetermined value or less of distance from a fluid particle among the fluid particles and a second particle with the predetermined value or less of distance from the first particle from among the wall boundary particles excepting the first particle;
setting a boundary condition of a pressure Poisson equation for calculating pressure to be applied to each of the particles;
calculating the pressure to be applied to each of the particles, based on the first particle and the second particle; and
calculating the particle data of the particles during a next time period based on the pressure,
the boundary condition includes that the first particle is set to a fluid particle whose velocity is a predetermined value and that pressure to be applied to the second particle is 0.

### Claim 3

A fluid simulating apparatus comprising:
a memory, and
a processor coupled to the memory and configured to perform a process including:
extracting, based on positional information included in particle data of particles, including fluid particles and wall boundary particles related to a boundary with a wall, during a predetermined time period, a first particle from among the wall boundary particles with a predetermined value or less of distance from a fluid particle among the fluid particles and a second particle with the predetermined value or less of distance from the first particle from among the wall boundary particles excepting the first particle;
setting a boundary condition of a pressure Poisson equation for calculating pressure to be applied to each of the particles;
calculating the pressure to be applied to each of the particles, based on the first particle and the second particle; and
calculating the particle data of the particles during a next time period based on the pressure,
the boundary condition includes that the first particle is set to a fluid particle whose velocity is a predetermined value and that pressure to be applied to the second particle is 0.

### Claim 4

A fluid simulating apparatus comprising:
a memory storing instructions;
a processor coupled to the memory and configured to execute the instructions to perform a process of:
detecting a plurality of particles including fluid particles and wall boundary particles related to a boundary with a wall in a fluid;
determining that one or more first particles of the plurality of particles are free fluid particles;
classifying one or more second particles of the free fluid particles as surface particles from which a neighboring particle is at a distance greater than an influence radius in at least one direction, and one or more third particles of the free fluid particles as internal particles which have neighboring particles at a distance equal to or less than the influence radius in all directions;
setting a boundary condition of a pressure Poisson equation to be applied to each of the plurality of particles based on the determining and the classifying so that a convergence of a solution is obtained when each of the free fluid particles flows in a gap of the fluid;
calculating pressure to be applied to each of the plurality of particles, based on the one or more first particles and the one or more second particles; and
calculating particle data of the one or more particles during a predetermined time period based on the pressure.

### Claim 5 (depends on 4)

The fluid simulating apparatus of claim 4, wherein the neighboring particle is treated as a fixed particle.

### Claim 6 (depends on 4)

The fluid simulating apparatus of claim 4, wherein the one or more second particles have fixed velocities.