[FabioT]

Hi, I am modeling a wind tunnel test with ICEM and Fluent.
Basically it is a box (cube=building) in a box (wind tunnel).


I need to describe as good as possible the turbulences and the detached flows around the bluff-body, especially in the corners.

In Fluent I will use different models, starting from kepsilon.

Question_1: I will need to have y+=1 close to the walls of the building, how can I do it?

I've already done a really coarse mesh to make an attempt and Fluent gives me values of the wall shear stress of ~0.03 Pa.

I tought then just to apply the formula

y+=[density*y*sqrt(shear_stress/density)]/viscosity

In my case, looking for y wich will be the dimension of the first step of the grid close to the wall:

density=1.225
shear_stress_wall=0.03
y+=1
viscosity=1.789*10^(-5)

yields to y=0.00009332 m

Does it make sense?
After the first cell how much can I increase the step distance?


Thank you very much, I attach a really coarse mesh as an example.

Question_2: Trying to make a mesh less coarse than the first one Fluent gives me a warning on the aspect ratio. But considering I have to model thevoundary layer and that the steps have to increase far from the walls for CPU reasons, I will always get low aspect ratio!
Suggestions?


Thank you very much for any reply!

Fabio