[Technical] Optimal cell sizes

anita · March 28, 2008, 07:47

Hi,

I have problems estimating the refinement of a mesh. Is there any rough rule of thumb? What attributes have to be considered?

Greetings,
Anita

dmoroian · March 28, 2008, 10:09

Hello Anita,
Check this for a grid spacing near the wall: YPlus Calculator.

I hope this will be helpful,
Dragos

mighelone · March 28, 2008, 11:13

Hi,

generally it is a good practice to perform a grid sensitivity analysis.
Start with a coarse grid and refine it until the results became independent from the grid size.

About the grid spacing near the wall you need to satisfy same value of y+ according with the turbulence model used.

A good starting point for y+ is to referring to a simple well-known problem, like i.e. the boundary layer in a flat plane.

Here http://geolab.larc.nasa.gov/APPS/YPlus/ a easy calculator of y+ is provided.

I hope this will be helpful

Michele

March 28, 2008, 07:47	Optimal cell sizes	#1
anita New Member Anita K. Join Date: Mar 2009 Posts: 25 Rep Power: 17	Hi, I have problems estimating the refinement of a mesh. Is there any rough rule of thumb? What attributes have to be considered? Greetings, Anita

March 28, 2008, 10:09	Hello Anita, Check this for a	#2
dmoroian Senior Member Dragos Join Date: Mar 2009 Posts: 648 Rep Power: 20	Hello Anita, Check this for a grid spacing near the wall: YPlus Calculator. I hope this will be helpful, Dragos

March 28, 2008, 11:13	Hi, generally it is a good	#3
mighelone Member Michele Vascellari Join Date: Mar 2009 Posts: 70 Rep Power: 17	Hi, generally it is a good practice to perform a grid sensitivity analysis. Start with a coarse grid and refine it until the results became independent from the grid size. About the grid spacing near the wall you need to satisfy same value of y+ according with the turbulence model used. A good starting point for y+ is to referring to a simple well-known problem, like i.e. the boundary layer in a flat plane. Here http://geolab.larc.nasa.gov/APPS/YPlus/ a easy calculator of y+ is provided. I hope this will be helpful Michele

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