Turbulence model for CFX moving mesh

songxguan · June 25, 2009, 08:12

Hello, everyone

I'm analyzing a safety valve using both transient flow and moving mesh.

First, I simulated the steady state using several turbulence model and compared these results with the test result, it's found that the k-w model got the best result and consumed lesser time.

The question is, can we use the k-w model as the turbulence model for the transient flow analysis with moving grid. It's said the such model as SST can get the better result for the steady analysis, but will become very cumbersome and expensive for unsteady simulation, since it need to calculate the distance from the wall after each iteration. I'm not clear that if k-w also need to do that.

Could somebody explain it ?

Thanks very much.

ghorrocks · June 25, 2009, 18:42

Hi,

The wall distance calculation does not take very long compared to the momentum and pressure equations. It should not slow things down too much.

Why don't you just try them both and see for yourself?

Glenn Horrocks

songxguan · June 25, 2009, 21:59

Thanks,

I did it.

not so big effect as you said.

Thanks.

csmistry · June 26, 2009, 06:54

I am a new usr also want to do directional control valve analysis from where to selct moving mesh.

ghorrocks · June 26, 2009, 07:19

Hi,

Sounds like you need to do some tutorials. There are several tutorials on the moving mesh capability - they will give you the basics.

Glenn Horrocks

csmistry · June 27, 2009, 07:24

Sir please tell me source for tutorial practice.

ghorrocks · June 27, 2009, 07:38

Hi,

Try Help/Tutorials. Was that so hard to guess where they could be?

Glenn Horrocks

songxguan · June 28, 2009, 21:05

if you use ansys cfx 12.0, you may have several selection for moving mesh: remeshing with ICEM CFD, solid commersed function(?) and full good hex mesh.

the help document doesn't give enough tutorial, you should find some more at the internet.

and if you really can't find any, you can contact me.

songxguan@gmail.com

June 25, 2009, 08:12	Turbulence model for CFX moving mesh	#1
songxguan New Member Xue-Guan Song Join Date: Mar 2009 Location: Busan, Korea Posts: 14 Rep Power: 17	Hello, everyone I'm analyzing a safety valve using both transient flow and moving mesh. First, I simulated the steady state using several turbulence model and compared these results with the test result, it's found that the k-w model got the best result and consumed lesser time. The question is, can we use the k-w model as the turbulence model for the transient flow analysis with moving grid. It's said the such model as SST can get the better result for the steady analysis, but will become very cumbersome and expensive for unsteady simulation, since it need to calculate the distance from the wall after each iteration. I'm not clear that if k-w also need to do that. Could somebody explain it ? Thanks very much.

June 26, 2009, 06:54	Valve	#4
csmistry Member mistry Join Date: Apr 2009 Location: India Posts: 69 Rep Power: 17	I am a new usr also want to do directional control valve analysis from where to selct moving mesh.

June 27, 2009, 07:24	Moving mesh	#6
csmistry Member mistry Join Date: Apr 2009 Location: India Posts: 69 Rep Power: 17	Sir please tell me source for tutorial practice.

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June 25, 2009, 18:42		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	Hi, The wall distance calculation does not take very long compared to the momentum and pressure equations. It should not slow things down too much. Why don't you just try them both and see for yourself? Glenn Horrocks

June 25, 2009, 21:59		#3
songxguan New Member Xue-Guan Song Join Date: Mar 2009 Location: Busan, Korea Posts: 14 Rep Power: 17	Thanks, I did it. not so big effect as you said. Thanks.

June 26, 2009, 07:19		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	Hi, Sounds like you need to do some tutorials. There are several tutorials on the moving mesh capability - they will give you the basics. Glenn Horrocks

June 27, 2009, 07:38		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	Hi, Try Help/Tutorials. Was that so hard to guess where they could be? Glenn Horrocks

June 28, 2009, 21:05		#8
songxguan New Member Xue-Guan Song Join Date: Mar 2009 Location: Busan, Korea Posts: 14 Rep Power: 17	if you use ansys cfx 12.0, you may have several selection for moving mesh: remeshing with ICEM CFD, solid commersed function(?) and full good hex mesh. the help document doesn't give enough tutorial, you should find some more at the internet. and if you really can't find any, you can contact me. songxguan@gmail.com