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Old   June 25, 2007, 09:19
Default about boundary layer and turbulence modeling
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mic
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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 ?
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Old   June 25, 2007, 10:08
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Ben
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15
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Old   June 25, 2007, 10:17
Default Re: about boundary layer and turbulence modeling
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mic
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15 what ?
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Old   June 25, 2007, 10:55
Default Re: about boundary layer and turbulence modeling
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Ben
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furlongs
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Old   June 25, 2007, 10:58
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mic
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it's a joke or an elegant way to say that i'm asking too much with too little detail ?
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Old   June 25, 2007, 11:13
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Ben
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it's a bad joke, it is monday after all.....
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Old   June 25, 2007, 11:21
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mic
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yeah, you're right...

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Old   June 25, 2007, 14:07
Default Re: about boundary layer and turbulence modeling
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a
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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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