Simulation of a coarse solid sphere settling in a riser with transverse vibrations

Abstract

During the transportation of the deep-sea ores in lifting risers, the vibration of the lifting risers due to oceanic currents and waves could exert an effect on the movement of coarse solid ores inside, such as transversal drag, collisions between the ore particle and inner wall of the riser. This study focuses on the settling behavior of a coarse sphere with a large Reynolds number in a transversal vibration riser so as to explore the effect of riser vibration on ore movement. In the present investigation, the moving computational domain, overset mesh, and hard-sphere collision model are applied. Then, the settling characteristics of the solid sphere with different riser vibration frequencies and amplitudes are mainly analyzed and discussed. The results demonstrate that with the increase in the vibrational frequency and amplitude of the riser, the relative velocity between the single solid sphere and riser in the vibration direction and the fluctuation of the sphere's settling velocity show an increasing trend, while the average settling velocity of the sphere decreases. The lateral velocity of the sphere, which is perpendicular to the vibration direction of the riser, is influenced slightly by the vibration frequency when the riser vibrates with a low frequency. In addition, the sphere trajectory is more chaotic at low vibrational frequencies compared to lower amplitudes and higher vibrational frequencies of the riser. The lateral displacement of the sphere is found to be suppressed when the vibrational frequency or amplitude of the riser is high enough.