For structured domains and unstructured domains used in a prism block the spacing of grid points adjacent to the domain is calculated. This function is intended to assist those building viscous grids since it provides near wall spacing in a very accessible manner.
The Wall Spacing function is a measure of the distance from each point on the domain to the adjacent point on the interior of the associated block. For this function the probe will render the point-to-point cell edge being measured at individual points on the boundary domain. Of course, the corresponding value will be labeled on the color bar.
Unstructured domains not in a prism block, structured domains in an unstructured block, and structured domains bounding a prism block have all values set to zero (0) for this function.
Tip: When creating viscous solution meshes, you should take advantage of the Wall Spacing and Wall Orthogonality functions to easily verify these mesh qualities on domains which lie on the geometry.