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-   -   about boundary layer and turbulence modeling (http://www.cfd-online.com/Forums/cd-adapco/56153-about-boundary-layer-turbulence-modeling.html)

mic June 25, 2007 09:19

about boundary layer and turbulence modeling
 
Hi. I'm coping with this fact: what should be the extent of the extrusion layer ?

I mean, i'm using a standard k-e model, with a standard wall function (local Re is high), how much space have i to take in account for the boundary layer ?

i thought a 3-layer with a thickness of 0.5(what are these numbers about ? Are maybe referred to the min and max cell lenght of the import geometry?) should be good...

Is there a way to calculate easy the boundary layer thickness ? I tried with the method y+ ='friction velocity * wall distance / dynamic viscosity, but i obtain nothing... any ideas ?

Ben June 25, 2007 10:08

Re: about boundary layer and turbulence modeling
 
15

mic June 25, 2007 10:17

Re: about boundary layer and turbulence modeling
 
15 what ?

Ben June 25, 2007 10:55

Re: about boundary layer and turbulence modeling
 
furlongs

mic June 25, 2007 10:58

Re: about boundary layer and turbulence modeling
 
it's a joke or an elegant way to say that i'm asking too much with too little detail ?

Ben June 25, 2007 11:13

Re: about boundary layer and turbulence modeling
 
it's a bad joke, it is monday after all.....

mic June 25, 2007 11:21

Re: about boundary layer and turbulence modeling
 
yeah, you're right...


a June 25, 2007 14:07

Re: about boundary layer and turbulence modeling
 
If you make the the cell reynolds number 1500 you generally get a decent Yplus for wall functions.

length is near wall cell height velocity is an estimate of the average free stream velocity


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