Ogrid on blade surfaces

topic

What rules are others using regarding establishing the thickness of the first row of grids adjacent to a turbomachine blade surface? I don't understand Adapco's explaination of the need to keep the value of y+ near the cells centroid (how do i translate from y+ to a physical distance). I am working with an incompressible fluid.

The nature of the problem is that the first row of cells must allow the software's built in log-law wall function to work properly.