A time-domain higher-order boundary element method for 3D forward-speed radiation and diffraction problems

摘要

A time-domain higher-order boundary element method for seakeeping analyses in the framework of linear potential theory is newly developed. Ship waves generated by two modified Wigley models advancing at a constant forward speed in calm water or incident waves and the resultant radiation and diffraction forces are computed to validate this code. A rectangular computational domain moving with the same forward speed as the ship is introduced, in which an artificial damping beach is installed at an outer portion of the free surface except the downstream side for satisfying the radiation condition. The velocity potential on the ship hull and the normal velocity on the free surface are calculated directly by solving the boundary integral equation. An explicit time-marching scheme is employed for updating both kinematic and dynamic free-surface boundary conditions, with an embedding of a second-order upwind difference scheme for the derivative in the x-direction to stabilize the calculation. Extensive results including the exciting forces, added mass and damping coefficients, wave profiles, and wave patterns for blunt Wigley and slender Wigley hulls with forward speed are presented to validate the efficiency of the proposed 3D time-domain approach. The corresponding physical tests of the radiation and diffraction problems in a towing tank are also carried out. Computed numerical results show good agreement with the corresponding experimental data and other numerical solutions.