Wall Functions: How do to decide on the y+?

Max Foamer · October 16, 2014, 10:51

I was trying to know in which range of y+ do I have to build my mesh at the walls, but I cannot find any information for the different WallFunctions.

Does anyone know on the necessary wall distance, for the wall functions included in OpenFoam? (nutUWallFunction, epsilonWallFunction, etc.)

Thank You.

gregjunqua · October 19, 2014, 20:48

If you are using a wall function. Your fist point of the grid should be where the logarithmic law is valid. it mean that 30<y+<(500-1000) to stay in the log layer. 500-1000 might be high.

Perhaps you can read :
CFD simulation of the atmospheric boundary layer : wall function problems
Blocken et al. 2007
Atmospheric Environment

for information about wall function you should search in the FOAM directory references are in the files most of the time.

Max Foamer · October 20, 2014, 04:40

Cheers!, I will definitely check it.

October 16, 2014, 10:51	Wall Functions: How do to decide on the y+?	#1
Max Foamer New Member Max Foamer Join Date: Oct 2014 Posts: 5 Rep Power: 11	I was trying to know in which range of y+ do I have to build my mesh at the walls, but I cannot find any information for the different WallFunctions. Does anyone know on the necessary wall distance, for the wall functions included in OpenFoam? (nutUWallFunction, epsilonWallFunction, etc.) Thank You.

October 19, 2014, 20:48		#2
gregjunqua Member Gregoire Junqua Join Date: Jun 2011 Location: China Posts: 58 Blog Entries: 1 Rep Power: 14	If you are using a wall function. Your fist point of the grid should be where the logarithmic law is valid. it mean that 30<y+<(500-1000) to stay in the log layer. 500-1000 might be high. Perhaps you can read : CFD simulation of the atmospheric boundary layer : wall function problems Blocken et al. 2007 Atmospheric Environment for information about wall function you should search in the FOAM directory references are in the files most of the time. __________________ ------------------------------------------------------- Gregoire Junqua Ocean University of China PhD Oceanography/ABL turbulence -------------------------------------------------------

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October 20, 2014, 04:40		#3
Max Foamer New Member Max Foamer Join Date: Oct 2014 Posts: 5 Rep Power: 11	Cheers!, I will definitely check it.