Hello, I'm trying to model a simple pipe. In this pipe is flowing water (ca. 2,0 m/s). In purpose to determine the Wall-shear-sress in high precision, I chose the Y+= 1. The solutions (Fluent 3) show that the values of Wall-shear-stress calculated by a grid with Y+=1 are much more discontinuous then values calculated by a grid with Y+=50. I think I did a mistake by building the grid (Gambit) or do the settings in Fluent. Is there something I have to consider while creating the grid (I used a B-layer with 4 rows )? How can I choose the settings in Fluent that the solver is able to calculate the Wss with high precision?

sincerely

Sorry there's a mistake: it's Fluent 6

If you are resolving the BL directly you need to use a turbulence model with compatible wall treatment.