# Is boundary layer "a must" in turbulence flow?

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 May 25, 2009, 06:06 Is boundary layer "a must" in turbulence flow? #1 New Member   Ping Join Date: May 2009 Posts: 3 Rep Power: 17 I wonder in modelling a turbulence flow, is constructing a boundary layer before meshing very necessary? Can we still run a turbulence model problem without it? And if the model is very complex, how are we suppose to calculate for the height of the first row in boundary layer???

May 25, 2009, 07:50
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 Originally Posted by Pingaroo I wonder in modelling a turbulence flow, is constructing a boundary layer before meshing very necessary? Can we still run a turbulence model problem without it? And if the model is very complex, how are we suppose to calculate for the height of the first row in boundary layer???

Hi ，Pingaroo

I would like to talk with you about this interesting issue.Yes, Ii is necessary to decide which turbulence model shoul be choosed to match our object.As all known, the Navier-Stokes equations is not closed themselves.Therefore, the turbulence model is indispensable.

Whether the model is quite complex or simple, the height of the first row is same to calculate before meshing grids.Here, I just ensure this problem.If you wonder knowing how to calculate the ds, I am also glad to discuss it with you .

Byron.25th,May.

 May 25, 2009, 11:09 #4 New Member   Ping Join Date: May 2009 Posts: 3 Rep Power: 17 Hi Byron and Ralf, Thank you for your replies. So basically boundary layer is a must when we need to focus on drag or heat transfer.... and is it always a good idea to check whether the turbulence model is in the wall yplus range? I know that we can calculate the height of the first row by using flat plates skin friction but it is for a very simple model. So, Byron would you please discuss more about complex model? __________________ CFD - ColourFul Diagram!!!