Hydrodynamic Behavior of a Submerged Spheroid in Close Proximity to the Sea Surface

Abstract

The principal objective of this investigation is to assess the hydrodynamic characteristics and the exciting forces induced by waves acting upon a shallowly submerged spheroid. This study focuses on an arbitrarily shaped spheroid body with a vertical axis, fully immersed beneath the free surface within waters of finite depth. The methodology outlined here necessitates solving the linear hydrodynamic diffraction and radiation problems, which entail discretizing the flow field around the body into ring-shaped fluid regions. Within each region, expansions of axisymmetric eigenfunctions of the velocity potential are employed. Complementing the theoretical framework, numerical methodologies are employed utilizing panel models across the wetted surface of the submerged body. Extensive numerical results concerning the exciting forces induced and the hydrodynamic coefficients are presented in the framework of frequency domain formulations. Through the current analysis, the phenomenon of negative added mass and rapid variations in the added mass and damping coefficients is confirmed, attributed to the free surface effect elucidated in terms of the presence of near-resonant standing waves above the submerged body.

Keywords

• diffraction and radiation problem
• exciting forces
• added mass
• damping coefficient
• theoretical and numerical formulation