problem stabilizing kw-sst..

backscatter · August 8, 2016, 05:45

Hi everyone,
I am encountering a strange problem while using kw-sst turbulence model in case of a 3d airfoil. In a very few steps omega and k both stop iterating (No of iterations = 0) and they seem to be converged, residuals being as low as 10^-15... I am using 10^-08 tolerance in the solver and 10^-04 as relTol... What could be the reason behind this behaviour?
Any help is appreciated..

NICKSUH · August 8, 2016, 06:30

What is the y+ value?

backscatter · August 8, 2016, 07:05

Yplus is 300

anishtain4 · August 8, 2016, 14:45

I think your yplus is out of the log layer. What is your boundary conditions for the airfoil?
Also you gotta check which variable goes unstable first? Other than that, you can try outputting your results more frequent and visually check what is going wrong? works more than you think.

shujaut · August 8, 2016, 15:25

thanks, i will try doing these first to see if i get it working...

August 8, 2016, 05:45	problem stabilizing kw-sst..	#1
backscatter Member Anonymous Join Date: Aug 2016 Posts: 75 Rep Power: 9	Hi everyone, I am encountering a strange problem while using kw-sst turbulence model in case of a 3d airfoil. In a very few steps omega and k both stop iterating (No of iterations = 0) and they seem to be converged, residuals being as low as 10^-15... I am using 10^-08 tolerance in the solver and 10^-04 as relTol... What could be the reason behind this behaviour? Any help is appreciated..

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August 8, 2016, 06:30		#2
NICKSUH New Member Hyoung Min Suh Join Date: Aug 2016 Posts: 4 Rep Power: 9	What is the y+ value?

August 8, 2016, 07:05		#3
backscatter Member Anonymous Join Date: Aug 2016 Posts: 75 Rep Power: 9	Yplus is 300

August 8, 2016, 14:45		#4
anishtain4 Senior Member Mahdi Hosseinali Join Date: Apr 2009 Location: NB, Canada Posts: 273 Rep Power: 18	I think your yplus is out of the log layer. What is your boundary conditions for the airfoil? Also you gotta check which variable goes unstable first? Other than that, you can try outputting your results more frequent and visually check what is going wrong? works more than you think.

August 8, 2016, 15:25		#5
shujaut New Member Anonymous Join Date: Mar 2016 Posts: 1 Rep Power: 0	thanks, i will try doing these first to see if i get it working...