[anita]

Hi,

I have problems estimating the refinement of a mesh. Is there any rough rule of thumb? What attributes have to be considered?

Greetings,
Anita

[dmoroian]

Hello Anita,
Check this for a grid spacing near the wall: YPlus Calculator.

I hope this will be helpful,
Dragos

[mighelone]

Hi,

generally it is a good practice to perform a grid sensitivity analysis.
Start with a coarse grid and refine it until the results became independent from the grid size.

About the grid spacing near the wall you need to satisfy same value of y+ according with the turbulence model used.

A good starting point for y+ is to referring to a simple well-known problem, like i.e. the boundary layer in a flat plane.

Here http://geolab.larc.nasa.gov/APPS/YPlus/ a easy calculator of y+ is provided.

I hope this will be helpful

Michele