Source terms will add/remove material or stuff from cells. You set the rates so you'd need contact area etc from the solver to get the phase change and would have to manually resolve everything. Â DEFINE_MASS_TRANSFER should handle most/all of the mass & energy for you, Â https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v241/en/flu_udf/flu_udf_MultiphaseDEFINE.html%23flu_udf_sec_define_mass_transfer
You are navigating away from the AIS Discovery experience