writing udf

rostamimass · April 23, 2011, 02:51

dear all
i am writing a source-udf. in that formula there is some derivative terms depending on time. i dont know how should i write them or which macro should use, for example there is d/dt(du/dy+dv/dx) in formula for source term. thanks

Amir · April 23, 2011, 14:13

Hi masumeh,
you know that this kind of UDF executes every iteration so, it's enough that you use global parameter and put the desired variable in, then in new time step use the parameter value for last time step and then put new one to it. (note that you should renew the global parameter every time step not every iteration)

April 23, 2011, 02:51	writing udf	#1
rostamimass New Member massoumeh Join Date: Mar 2011 Posts: 10 Rep Power: 15	dear all i am writing a source-udf. in that formula there is some derivative terms depending on time. i dont know how should i write them or which macro should use, for example there is d/dt(du/dy+dv/dx) in formula for source term. thanks

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April 23, 2011, 14:13		#2
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 23	Hi masumeh, you know that this kind of UDF executes every iteration so, it's enough that you use global parameter and put the desired variable in, then in new time step use the parameter value for last time step and then put new one to it. (note that you should renew the global parameter every time step not every iteration)