KR101214903B1 - System and method for fluid simulation using interaction between particles - Google Patents

Abstract

A fluid simulation method using interactions between particles comprises: generating a plurality of particles in a calculation region containing a fluid in a first time step; Creating an interaction condition between said particles among said plurality of particles produced in said first time step and other particles located within a predetermined distance from said particles; And calculating positions and velocities of the plurality of particles of at least one second time step based on the interaction conditions.

Description

Fluid simulation system and method using particle interaction {SYSTEM AND METHOD FOR FLUID SIMULATION USING INTERACTION BETWEEN PARTICLES}

Embodiments relate to fluid simulation systems and methods using particle interaction.

In the field of computer graphics (CG), especially in the field of visual effects (VFX), fluid simulation requires a great deal of computation, and therefore, a lot of research and development is required even in recent years with improved computer performance. On the other hand, studies to quantify the flow of fluid numerically before the birth of the CG field have been discussed in the field of Computational Fluid Dynamics (CFD).

Most of the fluid movements encountered in everyday life can be seen as incompressible fluid flow, and in the field of CG and CFD, the Navier-Stokes equation is used as the governing equation to interpret incompressible fluid flow. Doing. Navier-Stokes equations do not have an analytical solution because many different partial differential equations are combined into one equation, and it is not until the 1970s that numerical solutions have been available using computers.

Methods for describing fluid flow in a fluid simulation include the Euler technique using a grid and the Lagrangian technique using particles. Particle-based techniques are described in detail in Matthias Muller et al., 2003, entitled "Patricle-Based Fluid Simulation for Interactive Applications," which is hereby incorporated by reference in its entirety. However, the particle-based fluid simulation technique has a problem in that it takes a long time to calculate an adjacent particle to be interacted with every new frame.

According to an aspect of the present invention, in the conventional particle-based fluid simulations or fluid simulations using particles, it is possible to solve the problem of increasing computation time by finding new particles to be adjacent to perform interaction every frame. It is possible to provide a fluid simulation system and method using particle interaction.

According to an embodiment, a fluid simulation system using interaction between particles may include: a particle generation module configured to generate a plurality of particles in a calculation region including a fluid in a first time step; An interaction module for creating an interaction condition between the particles among the plurality of particles generated in the first time step and other particles located within a predetermined distance from each particle; And a simulation module that calculates positions and velocities of the plurality of particles in one or more second time steps based on the interaction conditions.

According to one or more exemplary embodiments, a fluid simulation method using particle interaction includes generating a plurality of particles in a calculation region including a fluid in a first time step; Creating an interaction condition between said particles among said plurality of particles produced in said first time step and other particles located within a predetermined distance from said particles; And calculating positions and velocities of the plurality of particles of at least one second time step based on the interaction conditions.

According to the fluid simulation system and method using the interaction between particles according to an aspect of the present invention, the interaction conditions are generated only between the newly generated particles in the same time step, the particles in each time step according to the interaction conditions By performing the interaction therebetween, there is an advantage that the calculation time of the fluid simulation using the particles can be reduced.

1 is a block diagram of a fluid simulation system using particle interaction according to an embodiment.
2 is a flow chart of a fluid simulation method using the interaction between particles in accordance with one embodiment.
3A to 3I are diagrams illustrating a fluid simulation process using interactions between particles, according to an exemplary embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a fluid simulation system using particle interaction according to an embodiment.

Referring to FIG. 1, a fluid simulation system using particle interaction according to an embodiment may include a particle generation module 10, an interaction module 20, and a simulation module 30. The fluid simulation system using the interaction between particles described herein is intended to simulate the movement of particles by reflecting the force caused by the interaction between particles in the fluid simulation, and configured to perform all computational processes of the fluid simulation. Does not necessarily include all of them. For example, a fluid simulation system using interparticle interactions may be configured to replace or add to some configurations of a conventional grid-based fluid simulation system.

Embodiments described herein may have aspects that are wholly hardware, partly hardware and partly software, or wholly software. For example, a unit, module, system, or the like herein may refer to hardware, a combination of hardware and software, or a computer related entity such as software. For example, a part, module or system may be, but is not limited to being, a running process, a processor, an object, an executable, a thread of execution, a program, and / or a computer. . For example, both an application running on a computer and a computer may correspond to a unit, module, or system described herein.

The particle generation module 10 may generate one or more particles according to predetermined conditions at each time step of the fluid simulation. For example, the fluid simulation divides the calculation region containing the target fluid into a finite element in the form of a grid including a plurality of cells, and each cell or each cell of the grid ( It may be performed by calculating a velocity field having a velocity value defined for a vertex corresponding to a vertex of a cell) in a plurality of time steps. At this time, the particle generation module 10 may generate a plurality of particles according to a predetermined condition defined for the velocity field of the fluid. However, the conditions for generating the particles are not limited to the above-described form, and the particles may be generated using other suitable conditions depending on the characteristics of the fluid to be simulated.

The interaction module 20 may generate interaction conditions between the plurality of particles generated at each time step by the particle generation module 10. Interaction conditions refer to a force defined between particles such that any particle affects the position and / or velocity of another particle. For example, the attraction force or repulsive force acting between the particles may correspond to the interaction conditions. The interaction module 20 generates interaction conditions only between particles generated in the same time step, and particle simulations in subsequent time steps may be performed according to the interaction conditions thus generated.

The simulation module 30 may apply particle interaction generated by the interaction module 20 to particles generated by the particle generation module 10 to perform particle simulation. That is, the simulation module 30 may calculate the position and / or velocity of the particles in a subsequent time step by applying the interaction condition between particles generated in the same time step and the interaction condition is defined. have. At this time, each particle may be influenced by an external force such as gravity or air resistance in addition to the force due to the interaction conditions defined between the particles.

The specific computational process of particle-based fluid simulation is described in Matthias Muller et al., Published in 2003, which is entitled to "Patricle-Based Fluid Simulation for Interactive Applications," which is hereby incorporated by reference in its entirety and is readily available to those skilled in the art. The detailed description is omitted since it may be understood.

2 is a flowchart of a fluid simulation method using interaction between particles according to an embodiment, and FIGS. 3A to 3K are diagrams illustrating a fluid simulation process using interaction between particles. A fluid simulation method using interaction between particles according to an embodiment will be described with reference to FIGS. 2 and 3A to 3K.

First, referring to FIG. 3A, a plurality of particles 301 to 310 may be generated according to a predetermined condition in the first time step of the fluid simulation (S1). The first time step refers to any time step in the fluid simulation performed in a plurality of time steps, and does not necessarily mean the first time step. For example, the first time step may be the Nth frame of the fluid simulation. A velocity field of the fluid to be simulated 300 may be defined based on the grating shown in the drawing. In this case, the predetermined condition may be determined based on a speed value and / or an acceleration value in the speed field.

Next, an interaction condition may be generated between each particle among the plurality of particles 301 to 310 generated in the above-described process and another particle located within a predetermined distance from each particle (S2).

That is, referring to FIG. 3B, other particles 302 to 304 located within a predetermined distance d from any one of the particles 301 to 310 generated in the first time step may be found. . In this case, the predetermined distance d may be appropriately determined based on the computational burden for performing the fluid simulation and the characteristics of the fluid to be simulated.

Referring to FIG. 3C, an interaction condition may be generated between the one particle 301 and the other particles 302 to 304 located within a predetermined distance d from the one particle 301. In the drawings attached to this specification, the interaction between the particles is visualized and displayed in the form of line segments connecting the particles for explanation. That is, FIG. 3C shows that an interaction condition is created between one particle 301 and each of the other particles 302-304.

Referring to FIG. 3D, with respect to the other particle 303 of the particles 301 to 310 generated in the first time step, another particle 301 located again within a predetermined distance from the one particle 303. , 304, 306, and 307. In addition, referring to FIG. 3E, an interaction condition may be generated between the one particle 303 and each of the other particles 301, 304, 306, and 307.

Referring to FIG. 3F, the process described above with reference to FIGS. 3B through 3E may be performed on all of the plurality of particles 301 to 310 generated in the first time step, thereby allowing the plurality of particles 301 to 310 to be separated. Interaction conditions can be created. As a result, the interaction condition may be generated only among the particles located within a predetermined distance from each other among the plurality of particles 301 to 310.

Referring to FIG. 3G, based on the interaction conditions between the plurality of particles 301-310 generated in the first time step, the plurality of particles in one or more second time steps subsequent to the first time step. Positions and / or speeds of the letters 301 to 310 may be calculated (S3). The second time step may be a time step following the first time step described above. For example, if the first time step is the N th frame of the fluid simulation, the second time step may be the N + 1 th frame. Alternatively, the second time step may refer to any frame after the N + 1 th frame.

By repeating the process described above with reference to FIGS. 3A to 3G to the last time step as a plurality of time steps proceed, a fluid simulation result reflecting the interaction between particles can be obtained. That is, the position and velocity of each particle may be calculated in a plurality of time steps.

For example, referring to FIG. 3H, in a second time step subsequent to the first time step described above with reference to FIGS. 3A-3G, a plurality of particles 311-317 may be generated again according to a predetermined condition. Can be. 3I, another particle located within a predetermined distance from the one particle 311 with respect to any one particle 311 of the plurality of particles 311 to 317 generated in the second time step. (312). In addition, referring to FIG. 3J, an interaction condition may be generated between the one particle 311 and the other particle 312.

Referring to FIG. 3K, the process described above with reference to FIGS. 3I and 3J is performed on all the particles 311 to 317 generated in the second time step, thereby generating a plurality of particles ( 311 to 317 may create interaction conditions between particles located within a predetermined distance from each other. Next, based on the interaction condition between the plurality of particles 311 to 317, the position and / or velocity of the plurality of particles 311 to 317 in one or more time steps subsequent to the second time step may be determined. Can be calculated.

According to the fluid simulation system and method using the interaction between particles according to the embodiments described above, the interaction conditions between particles can be generated only between the particles generated in the same time step. That is, an interaction condition is generated between a plurality of particles generated in an arbitrary time step, and the position and velocity of the plurality of particles in one or more subsequent time steps may be calculated based on the interaction condition. . Therefore, the interaction between the particles is made according to a predetermined interaction condition without having to perform the process of finding particles to interact at every time step, there is an advantage that the operation time can be shortened.

Fluid simulation method using the interaction between particles according to the embodiments has been described with reference to the flow chart shown in the drawings. While the above method has been shown and described as a series of blocks for purposes of simplicity, it is to be understood that the invention is not limited to the order of the blocks, and that some blocks may be present in different orders and in different orders from that shown and described herein And various other branches, flow paths, and sequences of blocks that achieve the same or similar results may be implemented. Also, not all illustrated blocks may be required for implementation of the methods described herein.

Further, the fluid flow simulation method using particle interaction may be implemented in the form of a computer program for performing a series of processes, which may be recorded on a computer-readable recording medium.

Although the present invention described above has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and variations may be made therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (6)

A particle generation module for generating a plurality of particles in the calculation region containing the fluid in each of the plurality of time steps;
Among the plurality of particles produced by the particle generation module, create an interaction condition between each particle and other particles located within a predetermined distance from each particle, but only between particles generated at the same time step. An interaction module for creating an interaction condition; And
And a simulation module for calculating the positions and velocities of the plurality of particles in the plurality of time steps based on the interaction conditions.
delete The method of claim 1,
And said interaction between said particles and said other particles located at a distance greater than said predetermined distance from said particles does not occur.
Generating a plurality of particles in the computational region containing the fluid in each of the plurality of time steps;
Create interaction conditions between the particles and other particles located within a predetermined distance from the particles, wherein the interaction conditions are generated only between the particles created in the same time step; Doing; And
And calculating the positions and velocities of the plurality of particles in the plurality of time steps based on the interaction conditions.
delete 5. The method of claim 4,
The fluid simulation method using the interaction between particles of the plurality of particles, the interaction between the particles and other particles located at a distance farther from the predetermined distance from each particle does not occur.

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