Velocity measurements of a free-surface turbulent flow over smooth and rough beds

Abstract

The effect of different types of surface roughness on a turbulent boundary layer was studied using 1D velocity measurements in a relatively high Reynolds flow. The roughness consisted of trapezoidal ribs with horizontal spacing and roughness height $k$. The roughness elements were aligned in a direction transverse to the flow. A series of 7 tests of fully rough turbulent subcritical flow over two-dimensional transverse repeated trapezoidal ribs was undertaken, in which the ribs were varied to give uniform rib spacing-to-height ratios of p/k = 6--36. Measurements of the velocity were carried out over a range of Reynolds numbers, 81735 $