A GENERALISED UNSTEADY HYBRID DES/BEM METHODOLOGY APPLIED TO PROPELLER-RUDDER FLOW SIMULATION

A generalised hybrid viscous/inviscid flow model for the hydrodynamic analysis of marine propellers is presented. A Boundary Element Method (BEM) to predict propeller perturbation under inviscid-flow assumptions is combined with a Navier-Stokes solver to describe the viscous, turbulent flow with propeller effects recast as volume-force terms from BEM. In the present study, the viscous flow solution is based on a Detached Eddy Simulation (DES) model valid for unsteady flows. A numerical application is presented by considering a notional propeller-rudder assembly, and results from the hybrid DES/BEM solution are validated by comparisons with full DES. The validation study demonstrates the capability of the proposed hybrid viscous/inviscid flow model to describe transient propeller-induced flow perturbation and of propeller/rudder interaction in spite of the fact that the geometry of propeller blades is not resolved but described via a simple and fast volume force model.