Computations Of Hydrodynamic CharacteristicsOf A Floating Amphibious Vehicle Using BEM

This effort is motivated by the necessity of real time simulation of the dynamics of a new landing craft, the Advanced Amphibious Assault Vehicle (AAAV), as it traverses the surf zone. The aim of the present work is to compute the hydrodynamic characteristics of the AAAV when subjected to large amplitude motions. The numerical study is done in the framework of inviscid and irrotational fluid flow with the aid of the three-dimensional nonlinear Boundary Element Code, ~DYNAFS~, developed at DYNAFLOW. Special contact nodes are implemented for elements along the intersection of the free surface and solid surfaces, on which the corresponding boundary conditions are imposed. Artificial absorbing conditions are employed over the free surface area far away from the vehicle, and are evaluated for their potential to reproduce the actual physics. Adaptive meshing and regridding techniques are used to improve the results. Added mass and damping coefficients are deduced from the computed forces and moments on the vehicle resulting from a prescribed motion. Systematic results are obtained for various vehicle motion amplitudes, sea state conditions, and local water depths.