first grid size for a given y-lus

morteza08 · February 2, 2011, 18:16

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

f-w · February 2, 2011, 19:03

http://geolab.larc.nasa.gov/APPS/YPlus/

morteza08 · February 2, 2011, 19:27

Quote:

Originally Posted by f-w

http://geolab.larc.nasa.gov/APPS/YPlus/

thank you dear friend
another question.. i mentioned that i want to model a flat plate.. is this calculator can be used for flow over any arbitrary geometry or this is only for flat plate?

f-w · February 3, 2011, 13:05

At the top of the page:

"This page provides a worksheet for estimating the normal spacing to be used in a viscous CFD grid. Estimates are for a turbulent flat plate in free air and are based on the Sutherland formula for viscosity."

It's a good starting point for arbitrary geometry. Run your simulation (not necessarily until convergence) and plot y+; then adjust mesh accordingly.

February 2, 2011, 18:16	first grid size for a given y-lus	#1
morteza08 Senior Member Morteza Join Date: May 2010 Location: Iran,Islamic Republic of Posts: 161 Rep Power: 16	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 2, 2011, 19:03		#2
f-w Senior Member Join Date: Apr 2009 Posts: 159 Rep Power: 17	http://geolab.larc.nasa.gov/APPS/YPlus/

February 3, 2011, 13:05		#4
f-w Senior Member Join Date: Apr 2009 Posts: 159 Rep Power: 17	At the top of the page: "This page provides a worksheet for estimating the normal spacing to be used in a viscous CFD grid. Estimates are for a turbulent flat plate in free air and are based on the Sutherland formula for viscosity." It's a good starting point for arbitrary geometry. Run your simulation (not necessarily until convergence) and plot y+; then adjust mesh accordingly.