Compared to calm water, the descent characteristics of a cuboid in uniform flow are more complex. On the one hand, the uniform flow interferes with the trailing vortices generated during descent, accelerating vortex street dissipation and affecting vortex-induced forces. On the other hand, the descending vortices cause deformation of the uniform flow. The interaction between these two phenomena makes predicting the descent motion of a cuboid in uniform flow extremely challenging. In this paper, we numerically and experimentally study a cuboid falling in water, with a focus on the generated vortex during the process. First, physical experiments are carried out in a wave tank, and trajectory of the cuboid during its falling in water is successfully captured by setting its specific initial speed and attitude. Next, we apply the computational fluid dynamics method to numerically simulate the cuboid falling in water for further exploration. Numerical results on the trajectory of the cuboid show good agreement with those measurement in the physical experiments. Furthermore, by examining the macroscopic motion and microscopic flow during a cuboid's descent in calm water and uniform flow, this study analyzes its descent behavior and wake vortex evolution. The impact of uniform flow on the trajectory and vortex dynamics is discussed, elucidating the coupled interaction mechanism between the ambient flow disturbance and the vortices induced by the cuboid. The results indicate that as the uniform flow velocity increases, the amplitude of the pitch oscillation grows significantly, while the amplitude of the roll motion is gradually suppressed.
Shi et al. (Thu,) studied this question.