Installation and licensing

System requirements

On a GPU outside this list, zCFD prints a warning, disables the GPU and runs on the CPU.

An AMD GPU (HIP) version is available on request.

Linux / Unix

If you are running Linux/Unix zCFD is provided as a stand-alone installer containing all the packages required to get started. The installer is available for download from the zCFD website. Once the zCFD installer has been downloaded run the install script and follow the prompts.

$ bash zCFD-icx-sse-impi-<INSTALL_VERSION>-Linux-64bit.sh

Then copy the licence file provided over email into the lic folder in the install directory.

$ cp zcfd.lic /<path to zCFD install>/lic/

Once zCFD has been installed the zCFD environment can be activated from a bash shell:

$ source /<path to zCFD install>/bin/activate
(zCFD)$

The zCFD environment's Python accepts further packages. With the environment active, pip install <package> installs into the zCFD installation, where the solver and any Python functions in a control file can import it. Packages installed with pip install --user, or into a separate virtual environment, are not visible to the solver.

Windows

zCFD can be run locally on windows machines if Windows Subsystem for Linux 2 (WSL2) is installed. To install WSL2, follow the Microsoft instructions which can be found here.

The chosen Linux distribution shouldn't have an effect on how the code runs, but the Linux distributions listed above are supported.

To access your Linux filesystem on Windows it can be useful to add a quick access link in file explorer. To do this, in the address in file explorer enter

\\wsl$\

This will show you the root folders for your installed Linux distributions.

The installer is available for download from the zCFD website. For WSL, download the standard Linux distribution. Once the zCFD installer has been downloaded run the install script from within the WSL2 environment and follow the prompts.

$ bash zCFD-icx-sse-impi-<INSTALL_VERSION>-Linux-64bit.sh

Then copy the licence file provided over email into the lic folder in the install directory.

$ cp zcfd.lic /<path to zCFD install>/lic/

Once zCFD has been installed the zCFD environment can be activated:

$ source /<path to zCFD install>/bin/activate
(zCFD)$

Licence

zCFD requires a licence. To obtain one, contact zcfd@zenotech.com. When zCFD starts, it looks for a licence in the following places:

1. Any licence file, such as zcfd.lic, in the directory from which the solver is started.
2. Any licence file in the lic directory of the zCFD installation, /<path to zCFD install>/lic/. This location is searched only when the zCFD environment has been activated.
3. The RLM_LICENSE or zenotech_LICENSE environment variable.

A licence file is any file whose name ends in .lic.

The environment variable can name a licence file:

export RLM_LICENSE=/path/to/licence/file

or a licence server, where port and host are the port number and hostname given in the licence file:

export RLM_LICENSE=port@host

A system that cannot reach the internet requires a local licence server. The RLM licence server rlm and the Zenotech licence server zenotech are installed in the lic directory of the zCFD installation. See http://www.reprisesoftware.com/admin/software-licensing.php for how to run them.

Checking the licence

To check the licence before submitting a job, run:

run_zcfd --check-license

zCFD checks out its licence for the installed version, reports it and exits. It needs no case or mesh. A served licence with a seat limit reports:

zCFD licence check passed
  zcfd-core       2026.10   4 seats         expires 31-mar-2027   5053@licserver
  zcfd-feat       2026.10   64 seats        expires 31-mar-2027   5053@licserver
  MPI ranks free now: 33

zcfd-feat needs one seat for each MPI rank, so a job of more ranks than are free waits or fails with error -22. The last column shows the licence server or licence file in use. If the checkout fails, zCFD reports the error code listed below and exits with a non-zero status.

Licence error codes

When a licence cannot be checked out, zCFD reports Error checking out license followed by the RLM status value, the product, the version and the number of licences requested, and then stops. The product is zcfd-core for the solver itself and ends in -feat for a solver feature. A feature is checked out once for each MPI rank.

The table lists the status values most often encountered. For any other value, see the RLM documentation at https://reprisesoftware.com/docs/isv/appendix/appendix-b-rlm-status-values.html or contact us.

During a run, zCFD confirms with the licence server every 30 seconds that the licence is still held. If the server stops responding, zCFD logs Connection to license server failed retrying and continues. If the connection is not restored within 10 minutes, zCFD stops with License heart beat failed.