Residual plot for transitional turbulence model in CFX-solver manager

ttu004 · March 22, 2014, 01:26

Hi all

I am simulating flow over an aerofoil w.r.t time using SST Gamma-theta model. I noticed that in CFX solver manager, plots (RMS Intermit and Rethetat) for transitional turbulence fluctuate a lot when compare to the Turbulence (KO-K-TurbKE, RMS O-TurbFreq ) residual plot.

My questions are
1. What are the meanings of these plots?
2. With the transitional turbulence RMS plot fluctuates vertically in a wider range than the Turbulence RMS plot, is my results stable and promising?

Thanks
Tom

ghorrocks · March 22, 2014, 04:36

The fluctuations are probably a laminar separation bubble jiggling about. This is a real effect and the transitional turbulence model also shows this jiggling.

So this effect MIGHT be real. Do a sensitivity study to convince yourself.

March 22, 2014, 01:26	Residual plot for transitional turbulence model in CFX-solver manager	#1
ttu004 New Member Tom Join Date: Oct 2013 Location: Auckland, New Zealand Posts: 24 Rep Power: 12	Hi all I am simulating flow over an aerofoil w.r.t time using SST Gamma-theta model. I noticed that in CFX solver manager, plots (RMS Intermit and Rethetat) for transitional turbulence fluctuate a lot when compare to the Turbulence (KO-K-TurbKE, RMS O-TurbFreq ) residual plot. My questions are 1. What are the meanings of these plots? 2. With the transitional turbulence RMS plot fluctuates vertically in a wider range than the Turbulence RMS plot, is my results stable and promising? Thanks Tom

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March 22, 2014, 04:36		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The fluctuations are probably a laminar separation bubble jiggling about. This is a real effect and the transitional turbulence model also shows this jiggling. So this effect MIGHT be real. Do a sensitivity study to convince yourself.