Learning Forum

[FaizanYounas]

I'm using DEFINE_MASSTRANSFER UDF in my simulations for condensation. The default LEE model UDF in the fluent returns the units of density, and the mass transfer rate in the fluent is given by kg/m^3s. So, while using the DEFINE_MASS_TRANSFER macro should my equation return the unit of density as like with the LEE model? Or it could be anything else. For example, a famous phase change model (Sun model) uses the eq for mass transfer that is returning the value in kg.K/J, as mentioned below. Is it correct while implementing it in the UDF?

Note: The lambda is implemented as a constant value in UDF and represents the thermal conductivity of the unsaturated phase. So the only units here are 'K' for temperature difference and J/kg for latent heat given by 'L'.

[DrAmine]

Yes: the source term should be in kg/m┬│s. The unit of the equation you are sharing is correct :)