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-   -   usage of UDS & UDM (http://www.cfd-online.com/Forums/fluent/39631-usage-uds-udm.html)

Tong February 14, 2006 13:36

usage of UDS & UDM
 
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.

Kharicha February 15, 2006 02:16

Re: usage of UDS & UDM
 
"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.

Tong February 15, 2006 11:32

Re: usage of UDS & UDM
 
Thank you.


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