The latest version of Xcompact3d only supports cmake based builds. The only requirements is a Fortran 90-compatible compiler and a working MPI library.

Minimum requirements

cmake version 3.20 and above

a recent modern Fortran compiler (ie, gfortran 9 and above

Source Download and Compilation

Xcompact3d sources can be acquired by cloning the git repository:

git clone

If you are behind a firewall, you may need to use the https protocol instead of the git protocol:

git config --global url."https://".insteadOf git@

Be sure to also configure your system to use the appropriate proxy settings, e.g. by setting the https_proxy and http_proxy variables.

The compiling process

The build system for Xcompact3d is based on CMake. It is good practice to directly point to the MPI Fortran wrapper that you would like to use to guarantee consistency between Fortran compiler and MPI. This can be done by setting the default Fortran environmental variable

export FC=my_mpif90

To generate the build system run

``cmake -S $path_to_sources -B $path_to_build_directory -DOPTION1 -DOPTION2 … ``

for example

cmake -S . -B build

By defult the build system will also download the 2DECOMP&FFT library and perform the build install using the Generic FFT backend. Version 2.0.3 of that library is the default for Xcompact3d building and all tests are performed against this specific version. If the directory does not exist it will be generated and it will contain the configuration files. The configuration can be further edited by using the ccmake utility as

ccmake $path_to_build_directory

To compile the sources

cmake --build $path_to_build_directory -j <nproc>

for example, when in the build directory

cmake --build . -j 8 will compile the code using 8 CPU cores.

Appending -v will display additional information about the build, such as compiler flags.

The executable file xcompact3d is located in the build/bin directory.


The testing suite for the xcompact3d solver is composed by 14 tests as follows

  1. Atmospheric Boundary layer (ABL) in neutral conditions (new set-up)

  2. Atmospheric Boundary layer (ABL) in neutral conditions (old set-up)

  3. Atmospheric Boundary layer (ABL) in convective conditions (old set-up)

  4. Atmospheric Boundary layer (ABL) in stable conditions (old set-up)

  5. Differentially heated cavity

  6. Turbulent Channel Flow with X as streamwise direction

  7. Turbulent Channel Flow with Z as streamwise direction

  8. Flow around a circular cylinder

  9. Flow around a moving circular cylinder

  10. Lock exchange

  11. Mixing Layer

  12. Turbulent Boundary Layer (TBL)

  13. Wind Turbine

  14. Taylor Green Vortex (TGV)

By default only the Taylor Green Vortex case is activated, while the full testing suite needs to be enable by using the BUILD_TESTING_FULL flag as

cmake --build $path_to_build_directory -DBUILD_TESTING_FULL=ON

or by using ccmake.

The tests are performed using CTest as

ctest --test-dir $path_to_build_directory

Every test is performed in a dedicated working directory that is located under the following path


All standard outputs from all test runs are collated under the file


together with additional files detailing additional informations such as the elapse time for the different tests and the eventual failed cases.

*Note* Some of the alternative options for FFT and IO backends required additional input * For MKL FFT the location of the MKL libraires needs to be passed to the configure as for the 2DECOMP&FFT installation with

export MKL_DIR=${MKLROOT}/lib/cmake/mkl

  • For ADIOS the installation directory needs to be passes to the configure as

cmake -S . -B ./build -DIO_BACKEND=adios2 -Dadios2_DIR=/path/to/adios2/install/lib/cmake/adios2

Both steps are necessary for correct linking of the target xcompact3d with the libraries

Known issues

Some issues with ADIOS2.

The tests performed under CTest rely on the CMake ability to properly find the MPI executable mpirun.

The build system will try to enforce consistency between the MPI Fortran used and the MPI executable, for the first iteration of the configure step.

In case no MPI executable is not found or correct please modify manually the MPIEXEC_EXECUTABLE by using

cmake -S . -B build -DMPIEXEC_EXECUTABLE=/correct/path/to/mpirun

or by using

ccmake $path_to_build_directory