For details regarding the equations, please refer to fluent theory guide: 14.7.2. Unidirectional Constant Rate Mass Transfer (

Ansys Fluent provides a UDF that you can use to input models for different types of mass transfer, for example, evaporation, condensation, boiling, and so on. Note that when using this UDF, Ansys Fluent will automatically add the source contribution to all relevant momentum and scalar equations. This contribution is based on the assumption that the mass "created" or "destroyed" will have the same momentum and energy of the phase from which it was created or destroyed.

If you are not able to access the link, please refer to this forum discussion:

Thank you