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-   -   User Fortran - Alter variables in runtime (http://www.cfd-online.com/Forums/cfx/77816-user-fortran-alter-variables-runtime.html)

ellevset July 5, 2010 08:42

User Fortran - Alter variables in runtime
 
Hi
Is it is possible to use User fortran to change simulation variables. For example applying a step function to the Soot Mass Fraction of the Magnusson Soot model.

Peter

ghorrocks July 5, 2010 19:01

Yes, it should be possible. Sounds like a bad idea as the numerics will be unstable. Why do you want to apply a step function to the mass fraction?

ellevset July 6, 2010 03:10

I agree, it does sound like a bad ideas, but I have been experiencing some problems with the soot model. The entire domain is filled with a small amount of soot, of the order 1E-05. Even far away from the combustion.

I thought perhaps adding a filter would solve this problem.

Another question on User Fortran. When you create subprocesses are they automatically calculated of every cell, or do you have to specify where the calculation is done?

ghorrocks July 6, 2010 18:37

In this case your suggestion sounds like a really bad idea. You should check the simulation setup, have a look at the tutorials or ask CFX support for a demo file. I can't see how your suggestion will help.

Read the documentation on user fortran about how it works. There are two approaches - and I will let the documentation explain what they are.


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