Numerical model for the fluid–structure interaction mechanics of a suspended flexible body

Abstract

This study investigates the dynamic vibration and static deformation of a long flexible underwater body suspended from the ocean surface. A numerical model is constructed by considering (i) the structural mechanics, (ii) hydrodynamic forces induced by vortex shedding, (iii) motion mechanics associated with the free bottom end of the suspended body, and (iv) the interactions among (i)-(iii). Numerical computations are performed by applying uniform vertical distributions of the ocean flow speed and a sheared distribution, and by varying the weight of the body at the free bottom end. Comparing the computed results of these cases elucidates the mechanics of the fluid–structure interaction of the suspended body. In particular, the sheared flow velocity profile allows the growth of multiple frequency components of vibrations in the flexible body. The frequency multiplicity at a point in the body arises from the vortex-induced vibrations excited at that point, and those that are excited in other regions then propagate to that point.