rubensamarojr / polymps

Moving Particle Semi-implicit (MPS) method with Polygon or Particle wall. C++/OpenMP code for physical simulation of fluid with presence of free surface

A C++ code for numerical modelling of free-surface flow 🌊 using Explicit, Weakly Compressible or Incompressible Moving Particle Simulation/Semi-implicit MPS method. Boundary walls can be modeled by polygonal mesh (triangles) or discrete layers of wall and dummy (ghost) particles.

See EXAMPLES in the folder input.

How to cite PolyMPS ?

If you use PolyMPS, please cite the following reference:

Amaro Jr, R. A. and Cheng, L.Y. "PolyMPS - An open source CFD solver based on Polygon walls in Moving Particle Semi-implicit (MPS) method", Software Impacts, 14. https://doi.org/10.1016/j.simpa.2022.100376

Forum

On the PolyMPS Discussions page you can ask questions, discuss about simulation issues, share ideas, and interact with other members.

Contents

• Dependencies
• PolyMPS workflow
• Input files
  • Foldernames, Filenames, Physical and Numerical parameters
  • Solid domain
  • Fluid domain
• Compile
• Run
  • on LINUX
  • on WINDOWS
• Json input filename
• Additional note
• Output
• Directories
• License

Dependencies

• GCC (GNU Compiler Collection)
• Eigen
• libigl
• JSON for Modern C++

In order to install C++ compiler (GCC) on windows, we recommend to install Cygwin. You can find here how to install Cygwin. The following Packages should be selected during the Cygwin installation:

• automake
• gcc-core
• gcc-fortran
• gcc-g++
• gdb
• libstdc++
• make

Eigen, libigl and JSON for Modern C++ are third party header-only libraries, i.e., they do not need to be separately compiled, packaged and installed to be used 😍.

PolyMPS workflow

Input files

Have a look at some examples in the folder input.

In order to run these examples, please, go to the directory input/grid and extract the compressed folder grid.zip in the grid directory itself.

Foldernames, Filenames, Physical and Numerical parameters

It is necessary to create a file (extension .json) and set all parameters.

Solid domain

1. ... using triangular meshes. It is necessary to create a file (extension .stl) with informations about the initial geometry.
2. ... using particles. Necessary to add one layer of wall particles (material ID = 2) and two layers of dummy particles (material ID = 3) in the .grid file.

Fluid domain

It is necessary to create a file (extension .grid) with informations about the initial geometry and some numerical and physical parameters:

• First line: 0
• Second line: number of particles
• Next lines in the columns:
  • material ID
  • initial coordinates of particles X Y Z
  • initial fluid velocities VX VY VZ (generally 0.0 0.0 0.0)
  • initial particle pressure P (generally 0.0)
  • initial presure average PAV (generally 0.0)

Compile

Code compiled and tested on Windows 7, and Linux CentOS 7 and Ubuntu64.

You can build the project in GNU/Linux using the makefile. Follow these steps (CPU version):

Clone this repository into your system using terminal in Linux, and Git BASH or command prompt (cmd) in Windows

git clone https://github.com/rubensaaj/polymps.git

Go to the folder polymps

cd polymps

Now, clone the third party libraries. You must run two commands

git submodule init

to initialize your local configuration file, and

git submodule update

to fetch all the data from the third party libraries.

Edit the Makefile file (if necessary) with a text editor.

Make sure the environment is clean and ready to compile

make clean

Execute make

make all

This should create a binary main in folder bin

Run

⚠️FIRST OF ALL, go to the directory input/grid and extract the compressed folder grid.zip in the grid directory itself. Check if dam1610_3D_fluid_lo0p010_mps.grid contains the data mentioned before in Fluid domain.

on LINUX

In the terminal, type

./bin/main

on WINDOWS

You can do this in two ways:

1st way - In the command prompt, type

bin\main.exe

2nd way - Move the main.exe from the folder bin to the root folder polymps. After that, double click on main.exe.

Json input filename

Type the name of the json input file (located in input directory), e.g.

MpsInputExample

You can specify a different case by changing numerical and physical parameters in the input json file. Also, input grid and stl files should be updated according your problem. We recommend that you rename the json file, e.g. case_02.json, and set a new name to output folder. After that, you can run PolyMPS at any time, and type the name of the new json input file, e.g.

case_02

Output

This code writes pvd (header file) and corresponding vtu files as output. Look in the output directory. You can visualize them by open the pvd file with Paraview 👀.

Directories

The PolyMPS contains several files and directories:

File/Folder	Description
eigen	library for linear algebra: matrices, vectors, numerical solvers, and related algorithms
include	header files
input	simple input examples (json, grid and stl files). Grid files compressed in a folder
libigl	geometry processing library
json	file that uses human-readable text to store and transmit data objects
output	ouput files (pvd, vtu and txt files)
src	source files
LICENSE	MIT License
Makefile	set of tasks to compile the program
README	text file

License

This project is licensed under the MIT License - see the LICENSE file for details.

polymps's Issues

some write error in code

polymps/src/MpsParticle.cpp

Line 988 in 16362ea

limDom[2][0] -= 0.5*partDist; limDom[0][1] += 0.5*partDist;

I think some wrong have happened here, it may be like following:
limDom[2][0] -= 0.5*partDist; limDom[2][1] += 0.5*partDist;

To-Do list

• Velocity Laplacian in the explicit part. Need particle-polygon search 2x.
• NPCD using look table like pnd
• BC wall pressure
• Print TXT file of the screen and output simulation info
• Json input jump over irrelevant data for the case
• Update branchs
• Mean pressure in corners. Perform a test.
• Find Libs that give all triangles near the particle, or at least the average of normals and distances.
• Typedef double real
• Typedef float real

A problem about checkParticleOutDomain()

polymps/src/MpsParticle.cpp

Line 1353 in fa0f3ca

vel[iLastParticle*3 ] = 0.0;

I think here have some problem. It should be vel[iLastParticle*3 + j] = 0.0;