sph readme

8/10/2019 SPH Readme

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Readme for program:

SPH Simulator

Readme

January, 2012

David Schellander

ChristianDoppler Laboratory on Particulate Flow ModellingJohannes Kepler University | Linz | Austria


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Christian Doppler Laboratory on Particulate Flow Modelling www.particulate-flow.at 3

Overview

2D - SPH Simulator

Smoothed Particle Hydrodynamics

File System

Project Structure

Geometry files

Simulation save files

Simulation video files

Variables

Future

Contact


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Overview

Main


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Smoothed Particle Hydrodynamics

Main

Meshfree Simulation of Flows

SPH overview can be found in many papers, especially in

Computerrgraphics

Typical SPH Simulations

Damm breaking problem

Free Surface flows

Used in computergraphics and movies for water

simulations


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File System

Main

Create Main folder with project name

Create in this folder, a folder with name simulation

Main folder:

Contains save files of project

Contains tempSave.txt

Temporary Savefile which can be used to restart

simulation if it is crashed

Subfolder simulation:

Contains particle positions at special time

Used for showing the simulation


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File System

Setup Project

Start the program

Click on Load Simulation

Select save file of project, or file to initialize project

Now working directory is loaded

Calculate from loaded simulation status

Show simulations which are already calculated



File System

Geometry File Structure

First line contains info if safe file or geometry file

Geometry\n

Second Line contains general Parameters

dt;gX;gY;timestep;time\n

Third line contains fluid parameters

dx;h;rhoInit;alpha;beta;c\n

Following line contains Geometry data

Each line represents one Geometry



File System


Possible Geometries

Line

Line;x1;y1;x2;y2;rho;isWall \n

Triangle

Triangle;x1;y1;x2;y2;x3;y3;rho;isWall \n

Rectangle

Rectangle;x1;y1;x2;y2;x3;y3;x4;y4;rho;isWall \n

The positions for rectangle and triangle geometries must be

set counter clockwise in correct order.

Circle

Circle;x1;y1;radius;rho;isWall \n



File System


First all fluid geometries must be declared

At the end, all wall and obstacle geometries can be declared

If two particles intersect, then only the first particle will be set!



File System

Save File Structure

First line contains info if safe file or geometry file

Safe\n

Second Line contains general Parameters

dt;gX;gY;timestep;time\n

Third line contains fluid parameters

dx;h;rhoInit;alpha;beta;c\n

Following line contains particle data

Each line represents one particle

posX;posY;velX;velY;rho;pressure;E;U;isWall\n

Such a file can easily be created for the initializing a simulation

with Office or OpenOffice



File System

Video file structure

Filename is: sim_time_%time.txt

With%time as actual simulation time

Used to sort files after loading

Each line contains particle data

nr;time;posX;posY\n



Variables

Variables

Variable Meaningdt Time step size in seconds

gX, gY Gravity in x and y direction

timestep Nr of timestep

time Simulation time

dx Initial distance between particles in m

h Smoothing length in m

rhoInit Initial density

alpha Alpha in viscosity model

(for water around 0,1 to 0,01)beta Beta in viscosity model

c Speed of sound (m/s)



Variables

Variables

Variable MeaningposX, posY Position of particle

velX, velY Velocity of particle

rho Density of particle

pressure Pressure at particle position

E Energy (not used)

U Internal energy (not used)

isWall 0 is fluid, 1 is wall

nr Particle number



Variables

Example projects

In directory examples

3 example projects can be found

One working with geometry data

Two with safe-files

Open it and run it, then you can use the simulation button to

show the simulation results



Future

Is there any?

Find idea how to display velocities in simulation

Can be easily extended to 3D problems, but its better to use

LIGGGHTS for complex 3D problems

3D needs much more particles Parallelization would be important in 3D



Contact

Contact

David Schellander Dipl.-Ing.

[email protected]


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Thank you for using or testingthis software

Dipl.-Ing. Schellander DavidContact and more details: [email protected]

ChristianDoppler Laboratory on Particulate Flow Modelling

Johannes Kepler University | Linz | Austria

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