Experimental Observations on Flow Characteristics around a Low-Aspect-Ratio Wall-Mounted Circular and Square Cylinder

The mean wake structures of a cube (square cylinder) and circular cylinder height-to-width aspect ratio 1.0, at Reynolds number 1.78 × 104 based on the obstacle width, were investigated experimentally. boundary-layer thickness was 0.14 height. study performed using thermal anemometry two-dimensional digital particle image velocimetry (DPIV). Streamwise observed in for both cylinders included well-known tip- horseshoe (HS)-,vortex pairs as well additional akin to base vortices. In addition tip-, base-, HS-vortices, near cube, two more counter-rotating streamwise structures, including upper inboard vortices, observed. existence vortices formed obstacles is unique observation has not been previously reported such low-aspect-ratio thin boundary-layers. A model arch-vortex evolution proposed, which arch deformed by external shear-flow explain base-vortices wake. weak dominant-frequency St = f0D/U? 0.114 across height while no discernible spectral peaks apparent cylinder. Cross-spectral analysis revealed shedding be symmetric (in-phase) arch-type predominantly anti-symmetric (out-of-phase) Karman-type cube. makes fundamental contributions understanding flow-field surrounding cylinders.