I am trying to simulate non-equilibrium condensation of steam in nozzles using Fluent with a custom wet steam model(using UDS and UDMs). Its a two equation model, the same one which is already implimented with Wet-steam model of Fluent. The equations can be found in this article.

https://www.sciencedirect.com/scienc...59431117302983

What I am doing is, solving two additional UDS equations along with NS equations with source terms modified for accounting the effects of condensation. The parameters are calculated using a DEFINE_ADJUST macro and saved in UDMs, while source terms are applied using DEFINE_SOURCE macros. I am using density based, unsteady, 2D, AUSM solver. I already finished making the UDF and setting up the case, but couldn't make things work in the way expected. The UDF is compiling and running properly at the beginning, but the results are not seems to be realistic and diverges most of the time.

So what I am seeking is, anybody here have experience with such a non-equilibrium condensation modeling in FLUENT? I can understand that, apart from writing up all equations and doing calculations, there have to be some tweaks/constraints setup to avoid divergence and problems during the course of solution.

Could someone have some suggestions/advises/ideas on the procedure I should follow to make things work? If somebody is interested, I am ready to share the UDF here.

Thanks in advance,