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

Abstract: Strong winds produced in storms and hurricanes have a destructive effect on
buildings, particulary on low-rise structures such as industrial complexes.
The damage often starts when the roof is teared off because of strong suction
pressures which are produced near corners and edges by the turbulent winds of
the atmospheric boundary layer. When the wind approaches the corner, two
vortices which generate extreme negative pressures, are formed.

A number of work has been conducted on the effect of turbulence on the corner
pressure field of low-rise buildings. However, there is still a need to
investigate the effect of the finest turbulence scales.

An experimental programme, which is the final part of a Master of Science in
Mechanical Engineering, was conducted to investigate the effect of fine scale
turbulence on the corner vortices of a rectangular prism, which is a common
representation of a low-rise structure. Experiments were conducted in a wind
tunnel using grid and rod configurations to produce turbulent flows.

The results from the grid generated turbulence show that both increasing
turbulence intensity and length scale increase the pressure coefficients,
although the mean pressure is reasonably constant for varying turbulence
length scale. Considering the finest turbulence scales, which were induced by
the rod, the largest effect was found when the rod was positioned in the
lateral direction slightly under the leading edge. Then, the fluctuating
pressure coefficient increased and the pressure field under the corner
vortices started to fluctuate at a frequency of 240 Hz, which is an
interesting phenomenon.