k-epsilon model to k-omega model

FluidKo · November 20, 2021, 01:51

I'm studing drivation of k-omega model from k-epsilon model.
But I don't know why one term in k-omega model is negligible unlike k-epsilon model.
I've done until here.

I can understand this equation.
But there is a problem for last term in omega equation
https://www.cfd-online.com/Wiki/Wilc..._k-omega_model
At here there isn't last term in upper picture.
I've heard the coefficient is zero near the wall.
What is the reason?
I'm not good at english because I'm Korean.
So I want not only reference but also specific spot in reference.
Thanks

FluidKo · November 20, 2021, 02:21

I found it

Paper: 'Reassessment of the Scale-Determining Equation
for Advanced Turbulence Models'

paragraph under equation (25)

"The last term is negligibly small as η»0 for
constant-pressure boundary layers because k-» constant as
η»0."

η represents height from plate.

Inner region is very very thin(η»0) and in inner region molecule viscosiy is dominant.
So there can't be turbulence kinetic energy as zero(constant).

November 20, 2021, 01:51	k-epsilon model to k-omega model	#1
FluidKo Senior Member Sangho Ko Join Date: Oct 2021 Location: South Korea Posts: 135 Rep Power: 4	I'm studing drivation of k-omega model from k-epsilon model. But I don't know why one term in k-omega model is negligible unlike k-epsilon model. I've done until here. I can understand this equation. But there is a problem for last term in omega equation https://www.cfd-online.com/Wiki/Wilc..._k-omega_model At here there isn't last term in upper picture. I've heard the coefficient is zero near the wall. What is the reason? I'm not good at english because I'm Korean. So I want not only reference but also specific spot in reference. Thanks

November 20, 2021, 02:21	Origin paper of Wilcox	#2
FluidKo Senior Member Sangho Ko Join Date: Oct 2021 Location: South Korea Posts: 135 Rep Power: 4	I found it Paper: 'Reassessment of the Scale-Determining Equation for Advanced Turbulence Models' paragraph under equation (25) "The last term is negligibly small as η»0 for constant-pressure boundary layers because k-» constant as η»0." η represents height from plate. Inner region is very very thin(η»0) and in inner region molecule viscosiy is dominant. So there can't be turbulence kinetic energy as zero(constant).

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