USRMST is subroutine in UDS (User Defined Subroutine) in Fluent 4.5 use for define mass transfer source term between phase.

I ever use URSTRM subroutine (overall source term). But I don't work coz I want to defind mass transfer from primary phase to secondary phase when run I find only mass contain of secondary change but mass of primary don't change. I don't know Y.

I think only overcome this error I must try to use USRMST subroutine, but I don't know how to active it -_-' If somebody ever use it plz give enlighten for me. (o_o")

Yeah! I know I know after all of my co-worker's trying. :'D

For active USRMST subroutine u must check Mass tranfer at Multiphase Parameters option. and go
\setup1\expert\UDS\Physical model and Yes forTwo-Phase Mass transfer model.
I think it may be advantage for another user who use UDS in Fluent 4.5.

Thanks a lot my co-worker.