On the impact of arbitrary two-dimensional sections

Abstract

When an object drops into the water a slamming load with high pressure on the body happens. Such an impact force often causes serious structure damage to the ships and offshore structures. The study of the water-entry impact problem is thus of fundamental interest and practical significance in naval architecture and marine engineering. We analytically study the water-entry problem of an arbitrary two-dimensional object. The linearized formulation of Wagner (1932) for wedges of small deadrise an­gles is adopted and extended to general body geometries with the boundary condition on the body satisfied exactly. For wedges and circular cylinders, we derive closed­form solutions by using the conformal mapping techniques for the exact solution of the boundary-value problem at any instant. The analytical solutions are confirmed by comparisons to the physical experiments and the fully-nonlinear simulation results for wedges and by comparisons to the existing experiments for circular cylinders. for arbitrary ship-like bodies, we also develop a general solution scheme based on the use of Lewis-form representation of the body geometry. It is applied to wedge and circular cylinder and agrees with the exact solutions very well. For illustration, the solutions for the case of parabolic section and a bow flare section arc also presented