Turbulent flow past a low-aspect-ratio finite wall-mounted circular cylinder at various degrees of upstream sheltering

Planar particle image velocimetry (PIV) was used to investigate the flow past a finite wall-mounted circular cylinder (FWMCC) immersed in a turbulent boundary layer and subjected to various degrees of upstream sheltering. The effects of upstream sheltering were investigated using one to four upstream FWMCCs positioned in tandem at various streamwise spacings and height ratios (defined as the ratio of the upstream cylinders height to the downstream cylinder height). The upstream FWMCCs were positioned at streamwise spacings of 2d and 6d, where d is the diameter of the cylinders. The upstream cylinders had a height ratio of h₁/h₂ = 0.5 and 1, where h₁ refers to the height of the upstream cylinders and h₂ denotes the height of the downstream cylinder. In all cases, the downstream cylinder was positioned in the same location and occupied approximately 20% of the incoming boundary layer thickness. The flow measurements were made at a Reynolds number of 60,000, based on the boundary layer thickness and freestream velocity. The results highlight the effects of upstream sheltering by multiple cylinders on the mean flow and turbulence past the downstream cylinder. Attention is focused on the changes to the downstream cylinder wake as a function of the incremental addition of upstream cylinders from one to four upstream cylinders.