Zenotech Ltd
+44 (0)117 906 1100

Frequently Asked Questions

We do our best to answer email questions about zCFD promptly, but you may find the answer here more quickly.


There is a user guide including instructions on code use and the control dictionary online at zCFD User Guide .
Yes - the technical reference guide provides a detailed mathematical description of the equations and models included in zCFD. The technical reference guide is included in the software distribution in the /docs directory.
We have open workshops each year and some of our partners provide professional training sessions. Please let us know if you would like to arrange a special training event.
You can ask specific questions on the CFD Online Forum and we will do our best to answer them, giving priority to users with licenses including forum-based support. You can also contact one of our Partners for additional frontline support.
Yes - we use the RLM license management system and zCFD will not run without a valid license. A free-usage license is automatically issued when zCFD is downloaded, and this license will last for 1 month. For an extension, just download the software again!
zCFD needs to be able to access licsvr.zenotech.com over TCP on ports 6053 and 6056 from the compute node on which zCFD is running. You may need to request changes to your firewall rules by your system administrator to allow zCFD to connect to the license server.
For free and academic licenses, an internet connection is needed because zCFD looks for a web-based license server. For in-house computing without internet access, we can cut special industrial and unlimited licenses that will access your own RLM servers. These will be configured to provide us with a monthly report on use.
No - EPIC will automatically include zCFD in the price of an on-demand computing resource. If you already have a license for zCFD and want to use EPIC, then EPIC can use your license instead.
Yes - zCFD has two main parts: (i) an open-source Python driver that can be modified by anyone, for any purpose including the creation of proprietary variants, and (ii) a closed source core that must have a valid license to run. The Python driver allows a high degree of customisation, including integration with other processes and data sources.
Our goal is to make high fidelity CFD simulation available and affordable. Free access means that anyone can start using zCFD at any time without having to find a budget. With unlimited scale on all other license types, you can run jobs with large meshes and complex physical models quickly to meet customer timescales. With on-demand licensing you can flex your capacity to meet demand.
There are two solvers in zCFD: (i) the finite volume solver and (ii) the high order finite element solver. The finite volume solver is a density-based, preconditioned, explicit code that can run turbulent simulations from Mach numbers of 0.001 up to 5. The finite element solver can run with polynomial accuracy of 0 (1 point per hexahedral cell) up to 4 (125 point per hexahedral cell) on meshes with tetrahedral, prismatic and hexahedral element types. Both solvers include near-wall modelling for turbulent boundary layers with automatic wall functions. These can include roughness models for rough surfaces.
Because zCFD is a combination of OpenMP for in-device parallelism and MPI for inter-device parallelism, it scales well. We have run strong and weak scaling tests on a variety of hardware and can show close to ideal scaling for most industrial test cases.
All of the code features are described in the online zCFD User Guide . Broadly, zCFD is designed for rapid and scalable solution of the Navier-Stokes equations (RANS, URANS, DES, LES) with standard initial and boundary condition types. We include roughness models and automatic scalable wall functions to match the local y+ values. Specialist models can be added by Zenotech or via our Partners.
zCFD uses an HDF5 file format for meshes in order to support parallel I/O. Unstructured meshes in many standard commercial and open-source formats can be converted using the Mesh Conversion tools . zCFD will generally transcribe existing boundary conditions to equivalent definitions.
zCFD will output convergence data as it runs in a standard CSV file format. Solution data will be written periodically to an HDF5 restart file. Surface and volume data can be exported in CGNS, EnSight or VTK format for easy viewing in ParaView. We also recommend the use of Python notebooks and several examples are included in the open-source zPost repository on GitHub.