School of Engineering, The University of Queensland
Abstract
The interaction between the wake generated from separation off a cylinder and turbulent structures evident in a boundary layer are of significant importance in understanding the flows for cooling towers, submerged and semi-submerged vessels. This investigation was conducted on a wall mounted circular cylinder 25.4mm in diameter in the near wake region using MCCDPIV (multi-grid cross correlation digital particle image velocimetry) using a PCO4000 CCD array with full resolution of 4008 x 2672 pixels2 per image. The investigation was conducted for (ReD ≡ DU / ν) of 3600 and 5400. It was seen in the mean after taking the ensemble average of the instantaneous results that a stagnation line was formed between x / D = 1 and 1.5 downstream of the cylinder. The region of the cavity wake was highly turbulent having the largest velocity fluctuations in this region. The shape of the stagnation line was also seen to change, where for the ReD = 3600 the stagnation line position from the cylinder changed for a given height above the flat plate surface at y / D = 0
