Hi there I was wondering if you could help me out with a similar problem.

I am modelling a micro channel with k omega SST turbulence and there is a constant heat flux also added at the wall of my micro channel. 

I have modelled the micro channel as a smooth flow initially and have been getting a Y+ of 1 for Reynolds of 40k approx., but when I add a roughness ks of 9.84e-5 the Y+ is now 200+. I don't understand what I need to do in order to get it back to Y+=1 again, I have played with the bias of the mesh and tried increasing the number of cells but very little happens.

I am trying to see the sublaminar layer in so that I can see the effects of heat transfer.