A stable and adaptive semi-Lagrangian potential model for unsteady and nonlinear ship-wave interactions

摘要

We present an innovative numerical discretization of the equations of inviscid potential flow for the simulation of three-dimensional, unsteady, and nonlinear water waves generated by a ship hull advancing in water. The equations of motion are written in a semi-Lagrangian framework, and the resulting integro-differential equations are discretized in space via an adaptive iso-parametric collocation boundary element method, and in time via implicit backward differentiation formulas (BDF) with adaptive step size and variable order. When the velocity of the advancing ship hull is non-negligible, the semi-Lagrangian formulation (also known as Arbitrary Lagrangian Eulerian formulation or ALE) of the free-surface equations contains dominant transport terms which are stabilized with a streamwise upwind Petrov-Galerkin (SUPG) method. The SUPG stabilization allows automatic and robust adaptation of the spatial discretization with unstructured quadrilateral grids. Preliminary results are presented where we compare our numerical model with experimental results on a Wigley hull advancing in calm water with fixed sink and trim.