EFFECTS OF SURFACE-ROUGHNESS ELEMENT SPACING ON BOUNDARY-LAYER VELOCITY PROFILE PARAMETERS

Turbulent boundary-layer velocity profiles over rough surfaces depend on the size, shape and spacing of the roughness elements. In this stud y, simple theoretical equations to predict the aerodynamic roughness l ength and displacement height as functions of element spacing density are developed when cubes are used as roughness elements. These paramet ers are also evaluated from wind-tunnel tests for various element spac ing densities. The experimental results agree well with the theoretica l equations. Dependence of the shear velocity (or surface drag coeffic ient), turbulence intensity and longitudinal turbulent length scale on the element spacing density are also evaluated from the experiments. (C) 1998 Published by Elsevier Science B.V. All rights reserved.