Flow around a near-bed horizontal circular cylinder mounted on a vertical wall

Abstract

Flow around a near-bed horizontal circular cylinder mounted on a vertical side wall is simulated numerically in this study. The purpose of the study is to investigate the flow characteristics around the junction area between the cylinder and two plane boundaries. The effects of gap to diameter ratio (G/D = ∞, 0.5 & 0.2), Reynolds number based on the diameter (ReD = 1250, 2500 & 5000) and the length to diameter (aspect) ratio (L/D = 10, 20 & 40) are investigated. It is found that the three-dimensional flow structures formed in the junction area between the vertical wall and the cylinder are strongly affected by the gap ratio. Highly three-dimensional flow structures (i.e. oscillations of horseshoe vortices) are observed in the influence of gap ratio and Reynolds number. The end effect induced by the vertical wall is limited within 0.7D in the spanwise direction, 0.5D upstream and 3D downstream of the cylinder. The extent of the end effect is not sensitive to the gap ratio, Reynolds number or the aspect ratio.