Turbulence suppression not converge

salvoxx86 · November 27, 2016, 12:31

I community, sorry for my bad english,
i encountered a problem with turbulence suppression model, i have a profile with a chord of 1.84 m, a prism layer high 0.3 mm with 19 nodes (i can't realize a prism layer more high). compressible flow, freestream inlet, ideal gas, steady, tourbulent, SST kw model, CFL 1, two dimensional, i have 1 millions of cells i 2D. When i use gammaRetheta the solution converge but there is a fluctuation of the pressure coeficient in laminar zone while i use turbulence suppression the solution not converge (high fluctuation of residuals, drag and lift). I suppressed the turbulence in varius zone but the problem is the same: never converge. How i can resolve this problem? thanks Salvo

Andrrrew · November 30, 2016, 16:46

Maybe you should modify Courant number... Just a question, how did you suppress turbulence?

Saima · December 1, 2016, 21:16

Quote:

Originally Posted by Andrrrew

Maybe you should modify Courant number... Just a question, how did you suppress turbulence?

that's right i had similar issue, i have modified in solver settings CFL to 50, plus k-E under relaxation factor reduced to 0.6

But i dont trust on my result as i am still getting reversed flow or re-circulation on outlet.

Andrrrew · December 2, 2016, 03:30

Quote:

Originally Posted by Saima

that's right i had similar issue, i have modified in solver settings CFL to 50, plus k-E under relaxation factor reduced to 0.6

But i dont trust on my result as i am still getting reversed flow or re-circulation on outlet.

Hi Saima, maybe you can help me too:
http://www.cfd-online.com/Forums/sho...d.php?t=180813

taillanm · December 2, 2016, 05:49

Andrrrew :
For turbulence suppression you should use the model they have implemented (Turbulence Suppression model).
After you have to specify on which surfaces you suppress turbulence, it means probably splitting the surfaces of your body.

Andrrrew · December 2, 2016, 06:19

Hi taillanm, okok thanks, mainly my problem is on Tke residual...
http://www.cfd-online.com/Forums/sho...d.php?t=180813
Can you help me to stabilize it?

taillanm · December 2, 2016, 09:40

Hi,
Indeed the residuals indicate a problem linked probably to the mesh quality.. How does your mesh look like

Andrrrew · December 2, 2016, 12:10

It's about 1200000 cells with some refinements, as usual, for similar naval applications

November 27, 2016, 12:31	Turbulence suppression not converge	#1
salvoxx86 New Member Salvatore Timpani Join Date: Nov 2016 Posts: 1 Rep Power: 0	I community, sorry for my bad english, i encountered a problem with turbulence suppression model, i have a profile with a chord of 1.84 m, a prism layer high 0.3 mm with 19 nodes (i can't realize a prism layer more high). compressible flow, freestream inlet, ideal gas, steady, tourbulent, SST kw model, CFL 1, two dimensional, i have 1 millions of cells i 2D. When i use gammaRetheta the solution converge but there is a fluctuation of the pressure coeficient in laminar zone while i use turbulence suppression the solution not converge (high fluctuation of residuals, drag and lift). I suppressed the turbulence in varius zone but the problem is the same: never converge. How i can resolve this problem? thanks Salvo

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November 30, 2016, 16:46		#2
Andrrrew New Member Andrea Join Date: Jul 2016 Posts: 25 Rep Power: 10	Maybe you should modify Courant number... Just a question, how did you suppress turbulence?

December 2, 2016, 05:49		#5
taillanm Member Join Date: Nov 2015 Posts: 57 Rep Power: 10	Andrrrew : For turbulence suppression you should use the model they have implemented (Turbulence Suppression model). After you have to specify on which surfaces you suppress turbulence, it means probably splitting the surfaces of your body.

December 2, 2016, 06:19		#6
Andrrrew New Member Andrea Join Date: Jul 2016 Posts: 25 Rep Power: 10	Hi taillanm, okok thanks, mainly my problem is on Tke residual... http://www.cfd-online.com/Forums/sho...d.php?t=180813 Can you help me to stabilize it?

December 2, 2016, 09:40		#7
taillanm Member Join Date: Nov 2015 Posts: 57 Rep Power: 10	Hi, Indeed the residuals indicate a problem linked probably to the mesh quality.. How does your mesh look like

December 2, 2016, 12:10		#8
Andrrrew New Member Andrea Join Date: Jul 2016 Posts: 25 Rep Power: 10	It's about 1200000 cells with some refinements, as usual, for similar naval applications