Wake interference effects for two finite cylinders: A brief review and some new measurements. (August 2019) - Sumner, D.
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 ( C D and C L ) 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 × 10 4 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 C D, C L 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. Highlights: Brief literature review for flow around two surface-mounted finite-height cylinders. New measurements of C D, C L, St for finite cylinders in a staggered configuration. Effects of aspect ratio, pitch ratio, and incidence angle are presented.