Simulating marine propellers with vortex particle method

The vortex particle method is applied to compute the open water characteristics of marine propellers. It is based on the large-eddy simulation technique, and the Smagorinsky-Lilly sub-grid scale model is implemented for the eddy viscosity. The vortex particle method is combined with the boundary element method, in the sense that the body is modelled with boundary elements and the slipstream is modelled with vortex particles. Rotational periodic boundaries are adopted, which leads to a cylindrical sector domain for the slipstream. The particle redistribution scheme and the fast multipole method are modified to consider the rotational periodic boundaries. Open water characteristics of three propellers with different skew angles are calculated with the proposed method. The results are compared with the ones obtained with boundary element method and experiments. It is found that the proposed method predicts the open water characteristics more accurately than the boundary element method, especially for high loading condition and high skew propeller. The influence of the Smagorinsky constant is also studied, which shows the results have a low sensitivity to it.