The k-Epsilon model

Suliman · July 11, 2019, 03:46

Hi

I have a question about the k-Epsilon model. It says that this model predicts excessive turbulent kinetic energy k at stagnation points! And that is why K-omega SST uses limiters of the production term to limit this problem. Can anyone elaborate on this point? Why k-Epsilon predicts high k at stagnation points? K should be low!

sbaffini · July 11, 2019, 10:10

Give a look here:

https://www.sharcnet.ca/Software/Ans...wo_eq_mod.html

equation 4-383 and the Kato-Launder modification. Basically, near stagnation points you still have high derivatives, which enter the k production term, which is non negative for incompressible flows.

You can see it as a Boussinesque hypothesis flaw rather than a problem of a specific model.

July 11, 2019, 03:46	The k-Epsilon model	#1
Suliman New Member zool Join Date: Apr 2019 Posts: 9 Rep Power: 7	Hi I have a question about the k-Epsilon model. It says that this model predicts excessive turbulent kinetic energy k at stagnation points! And that is why K-omega SST uses limiters of the production term to limit this problem. Can anyone elaborate on this point? Why k-Epsilon predicts high k at stagnation points? K should be low!

July 11, 2019, 10:10		#2
sbaffini Senior Member Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 2,190 Blog Entries: 29 Rep Power: 39	Give a look here: https://www.sharcnet.ca/Software/Ans...wo_eq_mod.html equation 4-383 and the Kato-Launder modification. Basically, near stagnation points you still have high derivatives, which enter the k production term, which is non negative for incompressible flows. You can see it as a Boussinesque hypothesis flaw rather than a problem of a specific model. Suliman likes this.

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