Hi: I will add a source term in the momentum equation. This term is related to the volume fraction of a phase (my case is multiphase flow). So I use DEFINE_ADJUST and UDS to calculate the source term. My question is that can I directly use C_UDSI(c,t,i) in DEFINE_SOURCE to get the source term which is define as a UDS in DEFINE_ADJUST? Or should I use UDM to store the UDS value in DEFINE_ADJUST, and then use C_UDMI(c,t,i) in DEFINE_SOURCE macro. Any help will be very much appreciated. Thanks.

"My question is that can I directly use C_UDSI(c,t,i) in DEFINE_SOURCE to get the source term which is define as a UDS in DEFINE_ADJUST"

yes you can directly use C_UDSI(c,t,i) in your source term...no storage is needed.

But an UDS is a calculated variable(convection-diffusion), if your C_UDSI(c,t,i) can be written as a function (formula) of other variable, you should store it as UDM, not UDS.

Thank you.