convergence limits

c120613 · April 8, 2010, 12:32

Dear all,

I'm working to simulate a fan on CFX and after the numerical simulation I saw that the residual level doesn't go down below E-3, E-4. Then I want to know which parameter I can play on, in order to achieve a residual level around E-5, E-6.

Kind regards

Domenico di Cugno

mach000 · April 8, 2010, 12:40

if you are simulating a steady run, you can reduce the timestep value.

if you are simulating a unsteady run, you have two possibilities:

a) reduce the dt

b) increase the number of the sub-iterations at every timestep

ghorrocks · April 8, 2010, 19:13

Again, this question has been asked a million times - please refer to the FAQ

http://www.cfd-online.com/Wiki/Ansys...gence_criteria

April 8, 2010, 12:32	convergence limits	#1
c120613 Member Domenico Join Date: Sep 2009 Location: Cranfield Posts: 48 Rep Power: 17	Dear all, I'm working to simulate a fan on CFX and after the numerical simulation I saw that the residual level doesn't go down below E-3, E-4. Then I want to know which parameter I can play on, in order to achieve a residual level around E-5, E-6. Kind regards Domenico di Cugno

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April 8, 2010, 12:40		#2
mach000 Member Ciro Cannavacciuolo Join Date: Mar 2009 Posts: 35 Rep Power: 17	if you are simulating a steady run, you can reduce the timestep value. if you are simulating a unsteady run, you have two possibilities: a) reduce the dt b) increase the number of the sub-iterations at every timestep

April 8, 2010, 19:13		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	Again, this question has been asked a million times - please refer to the FAQ http://www.cfd-online.com/Wiki/Ansys...gence_criteria