Boundary layer thickness
 

Hi. I try to find a formula for boundary layer thickness for Re numbers 10e7 and higher. All formulas I find are for lower Re noumbers. Can anybody help me?

Can you post the equations that you have used thus far? So we know which ones you have and have not tried?

Cheers,
T

i only use Y+ parameter in Fluent. In Gambit I set BL thickness "on eye". I find some equations but for Re 10e5-10e6. I have Re 10e7-10e8.
equation is delta=0,37*l/sqrt5(Re)

References
 

Here is a reference that might be useful

http://www.desktop.aero/appliedaero/...yertheory.html

Specifically:

http://www.desktop.aero/appliedaero/blayers/lambl.html

With an interactive applet where you can adjust the Reynolds Number:

http://www.desktop.aero/appliedaero/...blsummary.html

Thanks :D
Now I must translate this

I think you both make a confusion between the Boundary Layer (which is a physical model, specifically a simplification of the the Navier Stokes equations) and Gambit's boundary layer which is a geometrical entity.

What you probably need is an estimation for the height of the first row of cells at the wall in your mesh (the starting dimension in Gambit's boundary layer), you can estimate this for any Reynolds number using this calculator:

http://geolab.larc.nasa.gov/APPS/YPlus/

It is unfortunate that Gambit uses the notion of boundary layer for a geometrical entity, but this has nothing to do with the Boundary Layer equation or theory !!!

Do