CFX supports three types of momentum sources: isotropic loss model; directional loss model; and general momentum sources. The theory for these momentum source types is given in Momentum Sources in the CFX-Solver Theory Guide. To implement in CFX, you can find in the CFX-Modeling Theory Guide.

Just as a hint: you need to define a subdomain in the place, where the momentum source needs to be activated. The subdomain can be equal to the full fluid domain. Once the subdomain is defined, you can specify the momentum source (e.g. as a CFD expression) on the subdomain details panel.

Regards,

Dr. Th. Frank.

You can use UDF for additional source term. However, if the additional term is a constant value, you can incorporate it directly from the cell zones list.

Prashant Saini : The discussion was here about ANSYS CFX. CFX uses User-Fortran for the purpose, but most of the time there is no need for dealing with FORTRAN. The CCL expression language is powerful enough for many purposes. And CFX does not has cell zones, but subdomains. The other terms (UDF, cell zones) are belonging to Fluent terminology.

Regards,

Dr. Th. Frank.