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Hysteretic behaviour of the wind loading for two closely spaced surface-mounted finite-height cylinders in a staggered configuration
Hayden Karl Reitenbach, David Sumner

Last modified: 2018-04-26


The flow around two closely-spaced surface-mounted finite-height cylinders arranged in a staggered configuration was studied experimentally in a low-speed wind tunnel at a Reynolds number of Re = 6.5×104.  The relative thickness of the ground-plane boundary layer was δ/D = 1.4.  Measurements of the mean drag and lift forces were made for both the upstream and downstream cylinders. Two centre-to-centre pitch ratios (P/D = 1.125, 1.25) and four cylinder aspect ratios (AR = 9, 7, 5, 3) were tested.  For each combination of P/D and AR, the wind direction (incidence angle) was varied in small increments from α = 0° (tandem) to α = 90° (side-by-side). Over a small range of α near and including the side-by-side configuration, the two cylinders were found to experience significantly different wind loads depending on whether α was being increased or decreased. The critical wind direction at the edge of the hysteretic range was associated with a sudden change in the wind load and its direction. The range of α over which the hysteretic behaviour occurred, and the magnitude and direction of the changes in wind loading, were found to be complex functions of P/D and AR.


bluff-body aerodynamics; wake interference; surface-mounted finite-height cylinder; staggered cylinders; lift and drag forces

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