first grid size for a given y-lus
 

hi
i am going to model a turbulent flow over a flat plate.
if i want to extract a given y-plus, how can i set the first grid size?
is there any formula to calculate the distance between wall and first grid in a given flow?

thank you in advance

thank you dear friend
another question.. i mentioned that i want to model a flat plate.. is this calculator can be used for flow over any arbitrary geometry or this is only for flat plate?

At the top of the page:

"This page provides a worksheet for estimating the normal spacing to be used in a viscous CFD grid. Estimates are for a turbulent flat plate in free air and are based on the Sutherland formula for viscosity."

It's a good starting point for arbitrary geometry. Run your simulation (not necessarily until convergence) and plot y+; then adjust mesh accordingly.