OBSERVATIONS OF REYNOLDS-NUMBER SENSITIVITY IN THE SEPARATED FLOW REGION ON A BLUFF-BODY

Measurements have been made at both full scale and model scale of the surface pressures on a conventional low-rise, pitch-roofed building. T he full-scale measurements were made under natural strong wind conditi ons in a near-equilibrium atmospheric boundary layer. Replicated model -scale experiments were made in simulated atmospheric boundary-layer f lows at 1 : 100 scale in two wind tunnels. The transverse pressure dis tribution at the mid-length section of the building produced by a tran sverse wind has been examined for sensitivity to Reynolds number. The influence of changes in mean wind speed at full scale, and of changes in length scale between full scale and model scale is presented. Both sets of results support the hypothesis that the separated flow at the windward eaves of the building is Reynolds number dependent. Corrobora ting evidence was obtained from further full-scale and model-scale exp eriments on the same building by changing the conventional sharp-line eaves to a curved eaves: this produced predominately attached flow ove r the roof, for which no Reynolds number sensitivity was observed. (C) 1998 Elsevier Science B.V. All rights reserved.