COMPUTATION OF FREE-SURFACE VISCOUS FLOWS AT MODEL AND FULL SCALE BY A STEADY ITERATIVE APPROACH

This paper describes progress in the development of a method to compute viscous flow with free surface around a ship hull. The method solves the steady RANS/FS problem by iteration, using the formulation proposed by Raven & Van Brummelen (1999). It is being developed to provide a more efficient alternative for the usual time-dependent solution approaches, in order to permit practical application on dense grids in ship design work.
Applications are shown to a Series 60 hull at model and full scale; and to a tanker model. Computed scale effects on the wave pattern are confined to the stern wave system, as expected. Good agreement with experimental data is obtained; in particular, there is little sign of numerical wave damping even further from the hull. Computation times are quite modest.
A theoretical analysis of the numerical accuracy is carried out. For the standard version of the method, this shows that it has a numerical damping of wave components which is of third order in the mesh size; and a second-order numerical dispersion. This explains the high accuracy found. Based on the analysis an alternative scheme is designed which further improves the accuracy.