Numerical investigation of flow field characteristics around semi-submerged rectangular cylinders with rounded corners

Abstract

The investigation of flow field characteristics of the semi-submerged rectangular cylinder (SRC) with rounded corners is of crucial industrial importance, but it faces two main challenges: a deficiency in diverse research SRCs with rounded corners and a lack of thorough experimental and analytical investigations in this domain. To mitigate these deficiencies, the present study increases rectangular cylinder diversity by adopting SRCs with different rounded corners. In this regard, the flow field characteristics of the SRC are examined under varying Reynolds numbers and aspect ratios to expand the research framework. The RNG k-ɛ model within the OpenFOAM was verified for the rounded corners by comparing it with experiments for the submerged rectangular cylinder. Meanwhile, mesh convergence analyses are performed to validate the reliability of the simulated results for the SRC with rounded corners. The results are compared with those obtained from the SRC with sharp corners. It is found that the rounded corner effectively reduces the disturbance from the bottom vortex and decreases the mean drag force. However, its effect on lift force is relatively small. Regarding the variations in flow field characteristics, the Reynolds stress results show that the upstream rounded corner reduces the velocity fluctuations and induces shear layer separation. Meanwhile, it is found that as the rounded corner radius increases, the interference caused by the bottom vortex reduces, thereby decreasing the amplitude of the pressure field on the bottom. Moreover, increasing the upstream rounded corner radius reduces the extreme values of turbulence kinetic energy on the SRC bottom. The results show that the evolution of the bottom vortex can be evaluated by analyzing the trend of the shape factor in the boundary layer characteristics.