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-   -   How to mesh the 1st grid point? (http://www.cfd-online.com/Forums/main/14205-how-mesh-1st-grid-point.html)

Daniel October 7, 2007 09:44

How to mesh the 1st grid point?
 
How to mesh the 1st grid point?

I am very young to CFD world. I'm trying to use oodles to learn LES techniques. Now I have some problems about meshing.

I saw a paper on flow over a cylinder using Fluent, its meshing guideline is like this, Reynolds Number Flow Regime Yplus/First Cell Height Re < 1000 Laminar First Cell Height = Cylinder Radius/24 1000 < Re < 20000 Turbulent, Enhanced Wall Treatment Yplus < 10 Re > 20000 Turbulent, Standard Wall Functions Yplus > 30

Q-1. Why mesh like this? Is there any references on how-to mesh under LES and DNS? Sorry, I did not find help from <grid generation> and <Fluent Mannual>...

Q-2. Is that mean: If I use wall function, then I can set the 1st grid point at the place of y+=30? If I use not wall function, then I should set the 1st grid point at the place of y+=1?

Q-3. I heard "Laminar LES"=DNS, what does it mean? Is it mean that their mesh is identical?

Q-4. I see that the 1st grid point is decided by the flow state, but When I predict flow around a building on a certain Re for example, the laminar and turbulence coexist around the building, then how to decide the 1st grid point?

Thanks for your time:)

Daniel

Kasper October 8, 2007 02:27

Re: How to mesh the 1st grid point?
 
take a look at this..

http://www.cfd-online.com/Forum/fluent.cgi?read=52743


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