y+ values for DES

CFT · March 19, 2010, 02:06

Hi all

As far as I understand the DES uses RANS model at the boundary instead of wall function. However I notice in the results of the turbulence there is a y+ term. Can someone explain ?

thanks
CFT

denizen · March 19, 2010, 02:13

rans models at boundary works as usual (with and without wall function) it depends on options you choise.

Jade M · April 20, 2010, 17:55

Under "Meshing Requirements for DES," the manual states "The grid resolution requirement in the attached boundary layers is the same as that of a regular RANS solution (10-15 nodes in the boundary layer). In the DES region, the grid has to be designed in all three space dimensions to allow at least the resolution of the largest turbulent structures. As the largest grid spacing is used in the switch for the DES limiter, it is essential to have sufficient resolution in the spanwise direction (if it exists)."

Nothing is mentioned about y+. I would suspect that it shows up in the results for informational purposes or left over from RANS but that it's not critical? I'm not expert though.

March 19, 2010, 02:06	y+ values for DES	#1
CFT New Member CFT Join Date: Mar 2009 Posts: 15 Rep Power: 17	Hi all As far as I understand the DES uses RANS model at the boundary instead of wall function. However I notice in the results of the turbulence there is a y+ term. Can someone explain ? thanks CFT

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March 19, 2010, 02:13		#2
denizen New Member Join Date: Mar 2009 Posts: 25 Rep Power: 0	rans models at boundary works as usual (with and without wall function) it depends on options you choise.

April 20, 2010, 17:55		#3
Jade M Senior Member Join Date: Feb 2010 Posts: 148 Rep Power: 17	Under "Meshing Requirements for DES," the manual states "The grid resolution requirement in the attached boundary layers is the same as that of a regular RANS solution (10-15 nodes in the boundary layer). In the DES region, the grid has to be designed in all three space dimensions to allow at least the resolution of the largest turbulent structures. As the largest grid spacing is used in the switch for the DES limiter, it is essential to have sufficient resolution in the spanwise direction (if it exists)." Nothing is mentioned about y+. I would suspect that it shows up in the results for informational purposes or left over from RANS but that it's not critical? I'm not expert though.