# How can check the eddy viscosity at the wall with LES

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August 14, 2015, 02:21
How can check the eddy viscosity at the wall with LES
#1
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Sungjin Won
Join Date: Dec 2012
Location: Seoul/Republic of Korea
Posts: 12
Rep Power: 6
Hi, I checked my code based on 3D turbulent channel flow model (Re_tau=180).

Staggered grid which contains eddy viscosity at the center of grid is used.

Due to the properties are placed on the grid center, I confused about checking the properties of eddy viscosity at the wall. When I plot the time averaged eddy viscosity data, the tendency doesn't look like going to zero.

The data starts from y+ = 0.583690705381331.

Attached Images
 eddy viscosity.jpg (33.5 KB, 20 views)

 August 14, 2015, 07:57 #2 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,492 Rep Power: 40 The static Smagorinsky eddy viscosity model cannot give zero at wall... Usually, a dumping function is supplied

August 16, 2015, 04:38
#3
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Sungjin Won
Join Date: Dec 2012
Location: Seoul/Republic of Korea
Posts: 12
Rep Power: 6
Quote:
 Originally Posted by FMDenaro The static Smagorinsky eddy viscosity model cannot give zero at wall... Usually, a dumping function is supplied

As you said, static Smagorinsky eddy viscosity cannot give zero at wall.

But when if I wanna check the dynamic eddy viscosity, is there a way to check it?

August 16, 2015, 04:47
#4
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 3,492
Rep Power: 40
Quote:
 Originally Posted by sjwon1991 Thank you for replying! As you said, static Smagorinsky eddy viscosity cannot give zero at wall. But when if I wanna check the dynamic eddy viscosity, is there a way to check it?
in the dynamic procedure, the eddy viscosity function must go to zero at a wall, you can check by looking to the vertical profiles as you did in the previous figure

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