An efficient numerical method for solving two-dimensional water-entry problems is presented. An initial boundary value problem for the water impact is formulated in a 2-D wave tank and solved by a mixed Euler- Lagrangian method. The actual free surface is updated at each time step based on the equipotential boundary condition. For efficient computations, we use different discretization depending on the boundary surface. The wetted part of the body surface is discretized with panels while desingularized discrete sources are distributed above the free surface and inside tank walls. This combined source distribution method can reduce computational time and is efficient without loss in accuracy. It is verified by solving the water-impact problems of wedges and a modern ship bow section. The numerical results compare well with similarity solutions and experimental measurements.
A ship in rough seas may suffer from excessive motions that result in slamming or impact. The ship would experience impact loads with high impulsive pressure when the ship hull penetrates the water surface. Of concern are impact loads on bow flare, bottom, stern and wet-deck. These impact loads have a transient nature and can cause structural damage. Therefore, the evaluation of such impact loads is very important for the structural design of ships. The solution of the water-body impact problem dates back to von Karmam (1929). In the past, various theoretical and numerical methods have been proposed to solve more general 2-D water-entry problems. To name a few, these include similarity flow solutions for wedges (Dobrovol'skaya, 1969), matched asymptotic expansions (Armand and Cointe, 1986; Watanabe, 1986; Howison et al., 1991), nonlinear numerical methods (Greenhow, 1987; Zhao and Faltinsen, 1993), conformal mapping methods (Hughes, 1972; Mei et al., 1999) and CFD techniques (Arai et al., 1994; Varyani et al., 2000).
