Nr cells thin thickness
 

Hi everybody,
I'm working on a volume very thin, 1 mm thickness, with porous zone boundary condition imposed (the component is a burner of a boiler).
The lenght of the global domain is 300 mm, so this component is very critical and I have to decrease the number of cells to obtain a faster resolution in Fluent.
Do you think that 3 or 4 cells along the thickness are enough to obtain an accurate solution? Or I should put 8-10 elements?
This parameter is very important to decrease even the skewness, so the smaller, the better! :)
Thanks in advance