Wake interference effects for two finite cylinders: A brief review and some new measurements

Abstract

A brief review of the literature for the flow around two surface-mounted finite-height cylinders in a staggered configuration illustrates some of the additional complexity associated with changes in the cylinder aspect ratio (AR), the effects of downwash, the three-dimensional structure of the wake, and the presence of additional vortex structures. To date, however, few extensive systematic studies of centre-to-centre pitch ratio (P/D), incidence angle ( α), aspect ratio, boundary layer thickness on the ground plane (δ/D) and Reynolds number (Re) have been reported for two finite cylinders. Some new measurements of the mean drag and lift coefficients (CD and CL) and the Strouhal numbers (St) for two staggered finite cylinders, for AR = 9, 7, 5, and 3, P/D=1.125–4.5, and α = 0∘–90°, at Re = 6.5×104 and δ∕D=1.4, illustrate the moderating effect of the three-dimensional flow on the wind loading and vortex shedding behaviour compared to the flow around two infinite cylinders. These new results suggest some changes to the flow pattern boundaries and uncover some new trends in the CD, CL and St data with P/D and/or α; there is a need for new flow visualization, flow field measurements, and numerical simulations to advance physical interpretation.