Turning off equations during solution in CFX, like fluent.

adilsyyed · April 26, 2015, 08:25

In fluent, we can turn off an equation (say energy equation) at the start of the solution. After some iterations, we stop the solver and turn on the energy equation again.
This technique is very useful when initially the solution tends to diverge.
Is it possible to do this in ANSYS CFX?

KushalJ · April 26, 2015, 17:03

I think this should be doable through expert parameters in CFX. search for the expert parameters in ANSYS documentation or look in CFX-pre, Insert -> Solver -> Expert Parameter.

adilsyyed · April 26, 2015, 17:38

Quote:

Originally Posted by KushalJ

I think this should be doable through expert parameters in CFX. search for the expert parameters in ANSYS documentation or look in CFX-pre, Insert -> Solver -> Expert Parameter.

Seems like it should be there. I will thoroughly consult documentation and CFX-Pre for expert parameters. If there is any problem, I will come back here and post it.

Thank you Sir.

Thomas MADELEINE · April 27, 2015, 03:57

to select which equation you want to activate or deactivate :
go to expert parameter -> last tab "model override" -> and then select the equation you want to modify (by default it is on solving of course)

for the stability I would rather use an under relaxation parameter (in the expert parameter too) or play with the order of the calculation like something with the first order and no turbulence as initialization for example.

April 26, 2015, 08:25	Turning off equations during solution in CFX, like fluent.	#1
adilsyyed Member Adil Syyed Join Date: May 2012 Posts: 49 Rep Power: 13	In fluent, we can turn off an equation (say energy equation) at the start of the solution. After some iterations, we stop the solver and turn on the energy equation again. This technique is very useful when initially the solution tends to diverge. Is it possible to do this in ANSYS CFX?

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April 26, 2015, 17:03		#2
KushalJ New Member Kushal J Join Date: Apr 2015 Location: chicago Posts: 5 Rep Power: 11	I think this should be doable through expert parameters in CFX. search for the expert parameters in ANSYS documentation or look in CFX-pre, Insert -> Solver -> Expert Parameter.

April 27, 2015, 03:57		#4
Thomas MADELEINE Senior Member Thomas MADELEINE Join Date: Oct 2014 Posts: 126 Rep Power: 11	to select which equation you want to activate or deactivate : go to expert parameter -> last tab "model override" -> and then select the equation you want to modify (by default it is on solving of course) for the stability I would rather use an under relaxation parameter (in the expert parameter too) or play with the order of the calculation like something with the first order and no turbulence as initialization for example.