A computional fluid dynamics (CFD) module for FreeCAD

An advanced open source CAD integrated CFD preprocessing tool to enable automated one-stop CFD simulation

LGPL licensed, the same as FreeCAD

by Qingfeng Xia, 2015~2020 http://www.iesensor.com/HTML5pptCV

The team from CSIR South Africa, 2016 has significant contribution to this repo:

Oliver Oxtoby http://www.linkedin.com/in/oliver-oxtoby-05616835
Alfred Bogears http://www.csir.co.za/dr-alfred-bogaers
Johan Heyns http://www.linkedin.com/in/johan-heyns-54b75511

CSIR team has forked this repo into https://github.com/jaheyns/CfdOF, focusing on usability for new users and OpenFOAM. Meanwhile, this repo still targets at preparing real-world case files from FreeCAD goemetry for advanced users, which also means user needs to tweak the OpenFOAM case files in production environment. Features from CSIR fork may be picked up in the future if agreed, but CfdOF is GPL licensed.

changelog and roadmap at Roadmap.md

Please file bugs and feature request in https://github.com/qingfengxia/Cfd/issues, in the issue report, you can link to FreeCAD forum discussion thread.

LGPL license as FreeCAD

Features and limitation

This CFD module now have a subforum in FreeCAD's official forum, see the link: https://forum.freecadweb.org/viewforum.php?f=37

This module aims to accelerate CFD case build up. Limited by the long solving time and mesh quality sensitivity of CFD problem, this module will not as good as FEM module. For engineering application, please seek support from other commercial CFD software.

Features

Python script and GUI to run a basic laminar flow simulation is supported by Cfd Workbench. See example in FoamCaseBuilder/test
An independent python module, FoamCaseBuilder (LGPL), can work with and without FreeCAD to build up case for OpenFOAM https://www.openfoam.com/ so it can be used in automated CAD design and simulation pipeline, see example https://github.com/qingfengxia/CAE_pipeline
Coupling with FenicsSolver https://github.com/qingfengxia/FenicsSolver, a multiphysics FEA solver set, has been demonstrated in early 2018.
Topology optimisation (meshing and boundary setup remain valid during geometry topology change)

Features comparison with CfdOF forked

missing features:

cfMesh, snappyHexMesh meshing, however, Cfd module support import mesh generated by third-party mesher
dropped PyFoam dependency (I have a plan and it is half done)
porous model, multiphase model (I will not implement it)
support windows platforms by BlueCFD ( I support windows 10 only with WSL)
see more at CfdOF github

added features:

windows 10 WSL platform support, assuming Ubuntu LTS distro is used.
create new analysis from mesh file generated from external meshing tool (e.g. mesh generated from Salome) here is the link to a video demo
Fenics FEM solver, initial demonstration of support other CAE solver
boundary layer supported via gmsh, other mesh file format support (merged into Fem workbench of FreeCAD official)
FoamBoundaryWidget class to provide raw dict to override "CFdFluidBoundary" setting. It is an advanced boundary setting for OpenFOAM, specify key-value pair for some special boundary

Limitation:

turbulence model case setup is usable, but only laminar flow with dedicate solver and boundary setup can converge
OpenFOAM thermal solver is under development

Platform support status

Linux:

  Ubuntu 18.04 as a baseline implementation, but should works for other linux distribution.

Windows 10 with Bash on Windows (WSL ubuntu 16.04) support (tested on windows 10 v1803):

  Official OpenFOAM  (Ubuntu deb) can be installed and run on windows via Bash on Windows (WSL) Since version 1803 can piped process output back python, which is needed to detect OpenFOAM installation.  There is a tutorial to install OpenFOAM on windows WSL: <https://openfoam.org/download/windows-10/>, make sure OpenFOAM bashrc is sourced in `~/.bashrc`.   
  
  On FreeCAD v0.17 for windows, gmsh has been installed, but 'PyFoam' is not included to the FreeCAD's python2.7 bundle. However, `pip` bundled with FreeCAD does not work, instead, 'PyFoam' is downloaded and extracted to "C:\Program Files\FreeCAD 0.17\bin\Lib\site-packages".

For paraview, it is recommended to uninstall WSL's paraview by sudo apt-get remove openfoam5paraview54, to use windows version (make sure paraview is installed and on PAHT) for better 3D performance. paraview on WSL just does not work for me, although glxgears works on software rendering viaexport LIBGL_ALWAYS_INDIRECT=1.

MAC OSX (it may work, but not tested):

    As a POSIX system, it is possible to run OpenFOAM and this module, assuming OpenFOAM/etc/bashrc has been sourced for bash

Relationship with official FEM workbench:

CFD is a pure Python wokbench based on FEM workbench. Code for meshing, material database capacity are shared. FemConstraintFluidBoundary is written in C++ and included in official FreeCAD FEM module, similar are VTK mesh and result IO C++ code.

Used C++ classes (quite stable API):

FemAnalysis: DocumentGroupObject derived, extensible by python developer, FemGui.getActiveAnalysis()
FemSolverObject: FemSolverObjectPython extensible by python developer
FemMesh: extensible by python developer
FemConstraintFluidBoundary: maintained by Cfd developer
FemResultObject: created by Cfd developer (Qingfeng Xia), extensible by python developer

Imported Python classes (unstable, change frequency in daily build):

FemFluidMaterial: FemObjects.makeFluidMaterial() <Cfd/InitGui.py>
FemMeshRegion,
FemMeshDisplayInfo
FemSelectionWidgets.GeometryElementsSelection in _TaskPanelCfdFluidBoundary class

Adapted Python classes (to avoid frequent changes in Fem to break Cfd module)

CfdCommand from FemCommand or later named as FemCommandManager
CaeMesherGmsh from FemMeshGmsh

Installation guide

Prerequisites OpenFOAM related software

Debian/Ubuntu

Cfd module are now tested with Python3 on FreeCAD 0.19dev (official PPA has python3 build), pip command should be replaced with 'pip3' see more details of Prerequisites installation in Readme.md in FoamCaseBuilder folder

OpenFOAM (3.0+) sudo apt-get install openfoam once repo is added/imported

see more OpenFOAM official installation guide, make sure openfoam/etc/bashrc is sourced into ~/.bashrc

PyFoam (0.6.6+) sudo pip install PyFoam (see platform notes for Windows). In the future, this dependency will be removed. This module is Python3 compatible
matplotlib for residual plot (it is bundled with FreeCAD on Windows), gnuplot is not needed any longer. On ubuntu/debian, sudo apt-get install python-matplotlib
paraFoam (paraview for OpenFOAM), usually installed with OpenFoam.
gmsh, as it is requested by FemWorkbench, it is also used in CfdWorkbench for meshing, check the install and path setup by which gmsh

Optional packages
FenicsSolver: a wrapper to Fenics project, can be installed using pip: pip3 install git+https://github.com/qingfengxia/FenicsSolver.git#FenicsSolver after install Fenics, see FenicsSolver readme for details.

RHEL/Scientific Linux/Centos/Fedora:

should work Installation tutorial/guide is welcomed from testers

Qt5 and Python3 supported

There should be a FreeCAD 0.19 will release a Python3 support, since python for Qt5 (PySide2) is generally available and Python 2 will be not maintained since 2020. There should be little work on this Cfd module to support Python3, initial python3 has been tested since May 2019 with the official PPA 0.19-python3 dev on Ubuntu 18.04.

Install freecad v0.18 stable

After Oct 2016, Cfd boundary condition C++ code (FemConstraintFluidBoundary) has been merged into official master in stable v0.17

Make sure Gmsh function is enabled and installed. gmsh 3 has been bundled with FreeCAD v0.17 on Windows.

Install Cfd workbemch

use FreeCAD 0.18+ AddonManager

manually download from github

git clone https://github.com/qingfengxia/Cfd.git

symbolic link or copy the folder into <freecad installation folder>/Mod, or ~/.FreeCAD/Mod/ e.g, on POSIX system:

sudo ln -s (path_to_CFD) (path_to_freecad)/Mod/Cfd

Testing

All the following test may be implemented in CI.

unit test

As Cfd is not an official module, its unit test case will not be run in Test workbench, manually test: run

python3 -m unittest TestCFD

In Cfd module folder (otherwise, python module in Cfd is not importable for python). If FreeCAD is not installed to /usr/local/FreeCAD/, you need to update the FreeCAD module path statement, sys.path.append('/usr/lib/freecad-daily/lib')

Test CFD GUI

run the test by python test_files/test_cfd_gui.py without start FreeCAD GUI

to quickly run a gui test for FreeCAD GUI functions on command line

Test with prebuilt case

A simple example of a pipe with one inlet and one outlet is included in this repo (test_files/TestCase.fcstd). The liquid viscosity is 1000 times higher than water, to make it laminar flow. The video tutorial is here

The test case is built on Linux, on windows you need to regenerate mesh, and change the case working folder to use the example case

Turbulence flow case setup is also usable, see (test_files/TestCaseKE.fcstd), but Reynolds number is set to be 1000, otherwise, calculation will diverge due to bad tetragen mesh. Better CFD meshing is planned for cfmesh, perhaps, snappyHexMesh.

Johan has built a case, see attachment test procedure on freecad forum

In 2018, I have completed a new feature, integrate the external Salome meshing tool into FreeCAD and OpenFOAM workflow.

Test FoamCaseBuider package (only in Linux terminal mode)

There is a test script to test installation of this FoamCaseBuilder package, copy the file FoamCaseBuilder/TestBuilder.py to somewhere writable and run

python3 pathtoFoamCaseBuilder/TestBuilder.py

This script will download a mesh file and build up a case without FreeCAD.

Tutorial to build up case in FreeCAD interactively

Similar with FemWorkbench

make a simple part in PartWorkbench or complex shape in Partdesign workbench
select the part and click "makeCfdAnalysis" in CfdWorkbench

which creats a CfdAnalysis object, FemMesh object, and default materail

config the solver setting in property editor data tab on the left combi panel, by single click sovler object
double click mesh object to refine mesh
hide the mesh and show hte part, so part surface can be select in creatation of boundary condition
add boundary conditions by click the toolbar item, and link surface and bondary value
double click solver object to bring up the SolverControl task panel

select working directory, write up case, further edit the case setting up then run the case (currently, copy the solver command in message box and run it in new console)

Roadmap

see external Changelog.md

see external Roadmap.md

How to contribute this module

Cfd is still under testing and development, but we are planning to be merged into FreeCAD official.

You can fork this Cfd module (stay with official stable FreeCAD release) to add new CFD solver or fix bugs for this OpenFOAM solver by send pull request.

There is a ebook "Module developer's guide on FreeCAD source code", there are two chapters describing how Fem and Cfd modules are designed and implemented.

https://github.com/qingfengxia/FreeCAD_Mod_Dev_Guide.git where updated PDF could be found on this git repo

This is an outdated version for early preview: https://www.iesensor.com/download/FreeCAD_Mod_Dev_Guide__20161224.pdf

jontateixeira / Cfd