User Fortran - Alter variables in runtime

ellevset · July 5, 2010, 09:42

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, 20:01

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, 04:10

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, 19:37

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.

July 5, 2010, 09:42	User Fortran - Alter variables in runtime	#1
ellevset New Member Peter Join Date: Apr 2009 Posts: 8 Rep Power: 17	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

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July 5, 2010, 20:01		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	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?

July 6, 2010, 04:10		#3
ellevset New Member Peter Join Date: Apr 2009 Posts: 8 Rep Power: 17	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?

July 6, 2010, 19:37		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	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.