Analysis of scale effects in ship powering performance using a hybrid RANS-BEM approach

This paper discusses scale effects in ship powering performance using a hybrid RANS-BEM approach. The propeller action is included in the viscous flow analysis of the ship hull using body forces obtained from a potential flow analysis of the propeller with a boundary element method. The effective inflow to the propeller is determined by subtracting the induced velocities from the boundary-element method from the total viscous flow field. Apart from discussing the various scale effects that can be discriminated in the flow around a ship and a propeller, we will extensively discuss the details of the coupling procedure which were found to be non-obvious if accurate power predictions are to be obtained. The approach will be applied to a tanker for which differences in the performance between model scale and full scale will be shown.