Ship Stern Flow Calculations on Overlapping Composite Grids

A method for predicting the viscous flow around ship sterns is presented. Its main advantage is the flexible high-quality grid on which the governing equations and the boundary conditions are discretized. A set of overlapping grids on the hull surface are created either by hyperbolic marching from one of the boundaries or by cutting the surface by horizontal and vertical planes. Body-fitted volume grids are then grown hyperbolically out from the surface. At the outermost edge of the computational domain a background Cartesian grid is chosen and a sequence of finer and finer Cartesian grids is automatically generated to create a sufficiently smooth transition between the coarse edge grid and the fine body-fitted grid. The algorithm guarantees that there is sufficient overlap between all grids. The Reynolds-Averaged Navier-Stokes equations are solved on the overlapping grid using finite difference discetization. The equations are partially transformed and all variables are co-located. Pressure and velocities are coupled via a SIMPLE algorithm and Rhie Chow interpolation is used to avoid checkerboard oscillations. Computed results are compared with measured data for three different hulls.