[WUYing]

Hi,

I have a 3D flow over cylinder case in openfoam, and cannot use the postProcess utility to output wallShearStress (WSS) around cylinder (no-slip wall) due to some reason. So I try to calculate the WSS in paraview, but failed. Here are my steps:

(1) use Filter (Calculator): calculate mag(U) for all mesh grids
(2) use Filter (Gradients of Unstructured Dataset): generate grad(U) for all mesh grids
(3) use Filter (Calculator): calculate shear stress tau = mu * grad(U) for all mesh grids

Up to now, I have the shear stress tau. And the next step is to obtain the wall shear stress for cylinder wall.

(4) use Filter (Extract Block) to extract cylinder
(5) use Filter (Extract surface) to extract cylinder surface

Here mistakes appear. The values for U, mag(U), grad(U), tau are all zero because the no-slip wall has zero velocity. Although it seems that I find the reason but I don't know how to solve it. In order to calculate the WSS, maybe I need to extract the first layer mesh cells around cylinder but I dont know how to do it in Paraview...

I would be very appreciated if anyone could give me some help!!!

Thanks!