Abstract
Owing to the difficulties in the accurate calculation of the shear zone area, determining drag force (FD)applied on a rigid body swimming in a granular bed is more complicated compared with that on the semi-immersed flat plate. In this study, we simplified the shear zone, made three assumptions to describe the “wedge,” and introduced the inertial number in the dynamic friction coefficient. The results showed that the boundary conditions have little effect on the overall FD and it increases with the increase in the swimming velocity and immersion depth and decreases as the particle diameter increases. Furthermore, we modified the Coulomb passive-earth pressure model, which is based on various functions, including swimming velocity and immersion depth, to effectively predict FD. Thus, the modified model could successfully predict the respective FD on rigid bodies at different swimming velocities and immersion depths.