The effect of fine scale turbulence on the corner vortices ofa rectangular prism

Abstract: Strong winds produced in storms and hurricanes have a destructive effect onbuildings, particulary on low-rise structures such as industrial complexes.The damage often starts when the roof is teared off because of strong suctionpressures which are produced near corners and edges by the turbulent winds ofthe atmospheric boundary layer. When the wind approaches the corner, twovortices which generate extreme negative pressures, are formed. A number of work has been conducted on the effect of turbulence on the cornerpressure field of low-rise buildings. However, there is still a need toinvestigate the effect of the finest turbulence scales.An experimental programme, which is the final part of a Master of Science inMechanical Engineering, was conducted to investigate the effect of fine scaleturbulence on the corner vortices of a rectangular prism, which is a commonrepresentation of a low-rise structure. Experiments were conducted in a windtunnel using grid and rod configurations to produce turbulent flows.The results from the grid generated turbulence show that both increasingturbulence intensity and length scale increase the pressure coefficients,although the mean pressure is reasonably constant for varying turbulencelength scale. Considering the finest turbulence scales, which were induced bythe rod, the largest effect was found when the rod was positioned in thelateral direction slightly under the leading edge. Then, the fluctuatingpressure coefficient increased and the pressure field under the cornervortices started to fluctuate at a frequency of 240 Hz, which is aninteresting phenomenon.