Turbulent normal velocity fluctuations close to a wall

Abstract
Measurements of the normal velocity fluctuations in the immediate vicinity of a wall are made using a technique which does not interfere with the flow. It is found that (∼(v+2))1/2 =0.005y+2 for y+→0. Values of the normal intensity obtained by extrapolating measurements made with thermal probes are shown to be in considerable error.