first grid size and y-plus

morteza08 · February 2, 2011, 17:17

hi
i am going to model a turbulent flow over a flat plate.
if i want to extract a given y-plus, how can i set the first grid size?
is there any formula to calculate the distance between wall and first grid in a given flow?

thank you in advance

doodek · February 6, 2011, 12:45

Hi,
You can estimate first grid size and calculate problem in your solver. Then you should check y+ value in the first cell near wall. Depends on this value you can refine mesh (or use automatic mesh adaptation option in your solver, for example Fluent). It is iteration process. Typically one preliminary calculation is sufficient to ensure adequate y+ value in the first cell.

Regards,
doodek

February 2, 2011, 17:17	first grid size and y-plus	#1
morteza08 Senior Member Morteza Join Date: May 2010 Location: Iran,Islamic Republic of Posts: 161 Rep Power: 15	hi i am going to model a turbulent flow over a flat plate. if i want to extract a given y-plus, how can i set the first grid size? is there any formula to calculate the distance between wall and first grid in a given flow? thank you in advance

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February 6, 2011, 12:45		#2
doodek New Member Join Date: Oct 2009 Posts: 24 Rep Power: 16	Hi, You can estimate first grid size and calculate problem in your solver. Then you should check y+ value in the first cell near wall. Depends on this value you can refine mesh (or use automatic mesh adaptation option in your solver, for example Fluent). It is iteration process. Typically one preliminary calculation is sufficient to ensure adequate y+ value in the first cell. Regards, doodek