grid independence
 

Hi!
I'm doing simulation of an humid air laminar flow over a porous plate (2D model), I just specified a velocity(0.13 m/s) and the species concentration at the inlet and at the bottom of the porous plate a fixed concentration. The minium dimensionof the element I choose is 0.025 mm and the dimensions are 150x4,115 mm
The problem is that if i refine the mesh I get different values of the velocity for each grid (they vary between 0.136 and 0.144 m/s).
I tried to refine the grid doing gradient adaption (based on the velocity gradient) but the results still vary.
As solving method I used SIMPLE and pressure based.I tried both inlet inizialization and hybrid....what should I try next? thanks for any answers

While adapting, did you do refinement alone or coarsening too?

Just refining....but the problem was that I was using only the residuals to check convergence...when I increased the iterations for every mesh the results didi converge

Are you running steady or transient. If steady, then the refinement could be overdone and the solution is achieved only if proceeded in transient mode. Else your turbulence model may not function properly if your y+ goes below a certain value. Most likely the former than the latter