OpenFOAM-13 — Native Windows (MinGW-w64)

Unofficial native Windows port / modified fork of OpenFOAM Foundation OpenFOAM-13. Independent project — not affiliated with or endorsed by the OpenFOAM Foundation or CFD Direct.

A native Windows build of OpenFOAM Foundation OpenFOAM-13, built with MSYS2 UCRT64 / MinGW-w64. No WSL, no Cygwin runtime.

Upstream & provenance

This repository is a Windows-native port / modified fork of OpenFOAM Foundation OpenFOAM-13.

Upstream: https://github.com/OpenFOAM/OpenFOAM-13

Most files remain unchanged from upstream OpenFOAM-13. Windows-specific changes are layered on top to support native Windows builds with MSYS2 UCRT64 / MinGW-w64, MS-MPI, and Windows-specific runtime/linking behaviour. All changes are minimal and guarded (ifeq ($(WM_ARCH),mingw_w64) / #if defined(_WIN32)), so Linux behaviour is preserved and the toolbox compiles and runs from a normal NTFS directory — no case-sensitive attribute and no subst drive required.

This project is independent and is not affiliated with or endorsed by the OpenFOAM Foundation or CFD Direct.

Companion ThirdParty repository

Optional third-party components (Scotch) live in a separate sibling repository, ThirdParty-13-Windows — a Windows companion to OpenFOAM Foundation ThirdParty-13. It is not bundled inside this repository; clone it next to this one (see Quick build). MS-MPI is an external Microsoft dependency and is not vendored in either repository.

What works

• Full build: solvers 5/5, modules 45/45, legacy 15/15, utilities 133/137, src libraries 104/114 (105/114 with Scotch). The unbuilt items are external/Linux-only (real metis/ptscotch/zoltan, ParaView/TECIO readers).
• Serial: blockMesh → checkMesh → foamRun (e.g. incompressibleFluid/pitzDaily).
• Decomposition: decomposePar with the scotch method (Scotch built natively).
• Parallel: mpiexec -n 2 foamRun -parallel with MS-MPI.

Requirements

• Windows 10/11 (x64) — the Universal CRT ships with the OS.
• MSYS2 with the UCRT64 toolchain: pacman -S mingw-w64-ucrt-x86_64-gcc make flex bison
• Git
• Optional, for parallel: MS-MPI runtime (msmpisetup.exe) + SDK (msmpisdk.msi), both free from Microsoft.

Quick build

From an MSYS2 UCRT64 shell, clone this repo and its ThirdParty sibling side by side under a short base dir:

export OF13_ROOT=/c/OF13
git clone https://github.com/fralarco/OpenFOAM-13-Windows.git  "$OF13_ROOT/OpenFOAM-13-Windows"
git clone https://github.com/fralarco/ThirdParty-13-Windows.git "$OF13_ROOT/ThirdParty-13-Windows"

cd "$OF13_ROOT/OpenFOAM-13-Windows"
source scripts/windows/env.sh
cd "$WM_PROJECT_DIR" && ./Allwmake

This gives the recommended sibling layout (ThirdParty is a separate repo, not a sub-directory of the OpenFOAM clone):

/c/OF13/
  OpenFOAM-13-Windows/     # this repository
  ThirdParty-13-Windows/   # companion repo: Scotch + MinGW build helpers

./Allwmake builds Scotch from the sibling ThirdParty clone automatically (as on Linux) and skips it cleanly if the clone is absent — only method scotch; decomposition needs it. To reuse an existing tree instead, set export OF13_THIRDPARTY=/c/OF13WinNormal/ThirdParty before sourcing env.sh. Use ./Allwmake -j N to limit parallel compilation (default: all cores).

See BUILD_WINDOWS.md for details and options.

OpenFOAM 13 Windows Terminal

Double-click scripts/windows/OpenFOAM-13-Windows-Terminal.cmd — the preferred launcher. It opens the OpenFOAM environment in Windows Terminal (wt.exe) when available, and falls back to the MinTTY launcher scripts/windows/OpenFOAM-13-Windows-Shell.cmd otherwise. Either way it opens an MSYS2 UCRT64 shell that loads OpenFOAM, sets the MS-MPI variables, starts in $FOAM_RUN, and shows a compact banner with a modern prompt.

Override the install locations before launching:

set OF13_ROOT=C:\MyOpenFOAM
set MSYS2_ROOT=C:\msys64

(OF13_ROOT defaults to C:\OF13WinNormal, MSYS2_ROOT to C:\msys64; no admin required.) Inside the shell, of13help prints the workflow and of13status prints the environment. Verify:

echo $WM_PROJECT_DIR
which foamRun
foamDictionary -help
of13status

Terminal appearance (optional)

Windows Terminal is recommended for the nicest look. An optional profile and colour scheme (OpenFOAM Dark) is provided at scripts/windows/windows-terminal-profile.json: copy its scheme and profile blocks into your Windows Terminal settings.json (Settings → Open JSON file). The MinTTY fallback opens with matching dark colours automatically. The theme is purely cosmetic — OpenFOAM runs the same without it — and no font files are bundled (Cascadia Mono ships with Windows Terminal; the default font is used if it is absent).

Running a case (standard OpenFOAM workflow)

Use the normal OpenFOAM tutorial flow — copy a tutorial and run its Allrun:

cd $FOAM_RUN
cp -r $FOAM_TUTORIALS/incompressibleFluid/pitzDaily .
cd pitzDaily
./Allrun            # blockMesh, foamRun, ... via bin/tools/RunFunctions

Parallel tutorials work the same way: runParallel in RunFunctions uses mpiexec on Windows (MS-MPI), so ./Allrun on a parallel case just works. For a scotch/MS-MPI parallel case you first build Scotch and the MS-MPI Pstream once (see BUILD_WINDOWS.md).

scripts/windows/run_serial.sh and run_parallel.sh are Windows-port validation smoke tests, not the standard way to run OpenFOAM. Use them to check the toolchain; use ./Allrun for real cases.

Notes and limitations

• decomposePar uses the standard decomposeParDict syntax. For Scotch, method scotch; is enough — no libs (...) entry is required (the plugin is loaded on demand, as on Linux), and no manual turbulence libraries are needed either: wall-function BCs (nutkWallFunction, …) are read through the generic patch-field fallback. (Case-specific function objects may still use the normal OpenFOAM libs (...) when a case defines them.)
• Parallel uses MS-MPI (mpiexec). RunFunctions' runParallel calls mpiexec on Windows and keeps mpirun on Linux (override via $FOAM_MPIRUN). Parallel runs need MPI_BUFFER_SIZE set (the shell sets it).
• Serial and 2-rank parallel are validated; large-scale scaling is not benchmarked.
• Not built: real metis/ptscotch/zoltan, ParaView/TECIO/ccmio utilities (they need their own external SDKs).

Licensing

OpenFOAM is GPL-3.0; this fork keeps that license (COPYING). Third-party components and their licenses are listed in THIRD_PARTY_NOTICES.md.

OpenFOAM is a registered trademark of OpenCFD Ltd. This project is not approved or endorsed by OpenCFD Ltd or the OpenFOAM Foundation.