Published online by Cambridge University Press: 04 July 2016
Velocity defect law has been accepted as a universal velocity distribution for a turbulent boundary layer along a flat plate. The two necessary conditions for such a similarity to exist are not fulfilled with flat plate boundary layer having smooth or uniformly rough surfaces. Rotta has proved that a linear increase of surface roughness in the stream direction is necessary to ensure such a similarity. This note is an experimental investigation into turbulent boundary layer along a flat plate with linear increase of roughness height. It is obvious that, under such conditions, complete similarity characteristics are fulfilled.