Investigation into the effect of vortex distribution on the flow field around a semi-submerged rectangular cylinder with different aspect ratios

Vortex distribution affects the flow field variation of offshore structures at different aspect ratios (ARs; length-to-draft). This paper investigates the relationship between the vortex distribution and flow field around a semi-submerged rectangular cylinder (SRC) at a low Reynolds number (Re = 36300) using the OpenFOAM platform. First, vortex generation is explored, and then the influence of vortex distributions on the flow field around the SRC is analyzed. The numerical results show that when the SRC pierces the free surface, the wake region is different from the Karman vortex street due to the free surface. AR mainly affects the range of the wake region and the SRC bottom vortex. In terms of vortex generation and differences in vortex structure, the variations of the flow field around the SRC are significantly affected by the vortex at the bottom of the SRC.