This workbench aims to help users set up and run CFD analysis. It guides the user in selecting the relevant physics, specifying the material properties, generating a mesh, assigning boundary conditions and setting the solver settings before running the simulation. Where possible best practices are included to improve the stability of the solvers.

• Incompressible, laminar flow (simpleFoam).
• Basic material data base.
• Flow initialisation with a potential solver.
• Tetrahedral meshing using GMSH including multiple region meshing using FEM workbench functionality.
• Post processing using paraview.
• Porous regions and porous baffles.
• Runs on Windows 7-10
• Unit testing
• Cut-cell Cartesian meshing with boundary layers.
• Extension to turbulent using RANS (k-w SST).
• New case builder using a modular template structure

• Conjugate heat transfer.

Any system on which FreeCAD and the prerequisites listed below can be installed. The following have been tested:

• Ubuntu 16.04
• Fedora 24

• Windows 7 (tested)
• Windows 8 (not yet tested)
• Windows 10 (tested)

Not tested, but a POSIX system. Possible to install and run OpenFOAM.

=============================================

The CFD workbench depends on the following external software, some of which can be automatically installed (see below for instructions).

• Latest development version of FreeCAD (0.17 prerelease; git commit 11209 or later)
• OpenFOAM (version 4.0 or later)
• Gnuplot.py (version 1.8)
• Gnuplot
• Paraview
• GMSH (version 2.13 or later)
• cfMesh (version 1.1.2)

In Windows, it is suggested to download a pre-packaged version from https://opensimsa.github.io/download.html and consult the included README file. This package comes with the latest stable release of the CFD workbench and most dependencies already installed. For installation of additional dependencies, see below.

Alternatively, a recent FreeCAD build can be obtained from https://github.com/FreeCAD/FreeCAD/releases and the latest CFD workbench downloaded from https://github.com/jaheyns/CfdFoam\. After extracting the FreeCAD archive to a directory , the CFD workbench can be extracted to the folder \Mod\CfdFoam or to <Application Data>\FreeCAD\Mod\CfdFoam.

Whichever option is used, dependencies can be checked and installed conveniently from the CFD Preferences panel in FreeCAD. In the FreeCAD window, select Edit | Preferences ... and choose "CFD".

The OpenFOAM installation is via the blueCFD-Core package (version 2016-1), with which Gnuplot and Paraview come bundled. This can be installed manually using the above link, or by clicking the relevant button in the Preferences panel described above.

Set the OpenFOAM install directory in the preferences panel to <blueCFD install directory>\OpenFOAM-4.x (It will be automatically detected in the default install location.)

Likewise the Gnuplot-py module can be installed from the Preferences panel (not necessary if using Option 1), as well as cfMesh. cfMesh is automatically built from source inside the OpenFOAM environment if installed from the Preferences panel. Note that this is a lengthy process.

Choosing the "Check dependencies" option will verify that all prerequisites have been successfully installed.

The latest development version of FreeCAD can be obtained from the Ubuntu daily build packages. Alternatively, it can be built from the source code at https://github.com/FreeCAD/FreeCAD\.

As the CFD workbench is fully developed in Python the user is not required to compile any libraries in order to use it, and can directly copy the folder to /Mod/CfdFoam or to ~/.FreeCAD/Mod/CfdFoam

As an example, from the command line, use git to clone the CFD workbench

$ git clone https://github.com/jaheyns/CfdFoam.git

and create a symbolic link to the local FreeCAD instalation directory.

$ ln -s <path/to/CfdFoam>  <path/to/FreeCAD>/Mod/CfdFoam

This workbench is unfortunately not yet available under the FreeCAD-Addon-Installer.

Dependencies can be checked and some of them installed conveniently from the CFD Preferences panel in FreeCAD. In the FreeCAD window, select Edit | Preferences ... and choose "CFD". Manual installation is however required for OpenFOAM, Gnuplot, Paraview and GMSH, which should be installed using your distribution's package manager or the links above.

Set the OpenFOAM install directory in the preferences panel - typical install locations are /home/user/OpenFOAM/OpenFOAM-4.x or /opt/openfoam4 (It will be automatically detected in common default install locations.)

The Gnuplot-py package can be installed into Python using the Preferences panel described above, as well as cfMesh which will be downloaded and built from the source code inside your OpenFOAM installation if you have not already done so yourself. Note that this is a lengthy process.

Choosing the "Check dependencies" option will verify that all prerequisites have been successfully installed.

Please discuss issues on the CFDFoam dedicated FreeCAD forum thread.

It is asked that developers should only add functionality or code that is working and can be tested. Dead code, even portions included for possible future functionality, reduces function clarity and increases the maintenance overhead.

Unit testing is currently under development. Where possible, it is asked that all new functionality should be included in the unit test framework.

For consistency please follow PEP8

1. Use 4 spaces per indentation level (spaces are preferred over tabs).

2. Limit all lines to a maximum of 120 characters.

3. Break lines before binary operators.

4. Blank lines

   • Surround top-level function and class definitions with two lines.

   • Definitions inside a class are surrounded by a single line.

5. Imports should usually be on separate lines.

6. Comments

   • Docstrings always use """triple double-quotes"""

   • Block comment starts with a # and a single space and are indented to the same level as that code

   • Use inline comments sparingly. They are on the same line as a statement and should be separated by at least two spaces from the statement.

7. Avoid trailing whitespaces

8. Naming convention

   • ClassNames (Camel)
   • variable_names_without_capitals (Underscore)
   • CONSTANTS_USE_CAPITALS (Uppercase)
   • functionsWithoutCapitals (Camel instead of underscore to ensure consistency with FreeCAD)
   • __class_attribute (Double leading underscore)

Oliver Oxtoby (CSIR, 2016-2017) ooxtoby@csir.co.za
Johan Heyns (CSIR, 2016-2017) jheyns@csir.co.za
Alfred Bogaers (CSIR, 2016-2017) abogaers@csir.co.za
Qingfeng Xia, 2015