A wind-tunnel investigation of the wind speed and turbulence characteristics close to the ground over various escarpment shapes

Abstract

A wind-tunnel investigation of the wind flow over two-dimensional forward-facing escarpments is reported as part of a continuing research programme into the effects of local topography on the wind flow close to the ground. Four sharp-edged escarpments with their slopes varying between a cliff and a 4:1 gradient, were placed normal to a simulated neutrally-stable rural boundary layer which was modelled to a scale of 1:300. The resulting flows close to the surfaces of the escarpments were measured with a hot-wire anemometer. The modifications to the mean wind speed, turbulence intensity and energy spectra over the escarpments are described. The results indicate the extent and magnitude of the modification to the flow and suggest that significant changes in turbulence characteristics only occur in the wake region close behind the crest, where a shift of energy to higher frequencies is evident.