First off, the vorticity is defined as the curl of velocity, or the gradient cross-product with the velocity field. In viscous flow, velocity should be zero at the wall, a boundary condition that causes the build-up of the boundary layer. So, unless you have a slip condition in the computation of the flow, your vorticity should be zero at the wall.
Second, if you see variables in the contour dialog for contours on surfaces, those variables are typically read in from your dataset. I'm not seeing where they are computed from the analyzer.
Aerospace Research Engineer
NASA Langley Research Center