Roll response of ship-hull sections in variable bathymetry regions by a hybrid BEM- vortex particle method

A non-linear, hybrid method has been developed with application to the problem of roll response of ship-hull sections of general shape, floating in general bathymetry regions. Using domain decomposition, the present method is based on boundary element formulation for the representation of the non-linear potential wave motion around the floating body, in combination with vortex particle method for the generation of vorticity in the boundary layer and numerical simulation of vorticity convection and viscous diffusion in subregions close to the solid boundary. Subsequently, hydrodynamic forces on the floating body are obtained by pressure integration, and the hydrodynamic coefficients (added mass, damping) are calculated. Numerical results are presented and compared with experimental data and other methods. It is shown that the present method provides results of reasonable accuracy, illustrating that the mixing of boundary integral methods and particle methods is a useful tool for the evaluation of ship-hull characteristics in rolling motion, where viscous effects associated with boundary layer separation could be significant.