Re: airfoil in OpenLB
for high Reynolds numbers you need to apply a turbulence model (e.g. SmagrosinskyBGKdynamics). To do this you have to change the the dynamics, you can have a look at the nozzle3d example, I think about line 349.
For small Reynolds numbers, what do you mean with “symmetric profile”? As far as i understand you are using a contant inflow velocity over the whole inlet? In this case you could check the corners, since there could occur some errors due to the non-smooth transition. Another problem could be the obstacle itself. If there is almost no angle of attac the obstacle maybe is just one cell thick? Such thin spikes can cause numerical errors, maybe increasing the resolution of the grid helps at this point.