Simplified test program for hydrodynamic CFD simulations of wind-powered cargo ships

Abstract

Four practical simplifications for modeling the hydrodynamic properties of a wind-powered cargo ship with CFD and a route simulation model is evaluated. We first test how much the drift-induced hull forces are dependent on Froude number, model scale, and heel angle. Then, we test the mathematical assumptions in the MMG maneuvering model, with particular focus on the rudder resistance as a function of drift angle, rudder angle and propeller thrust. The overall goal is to see if the hydrodynamics of the ship can be modeled with both a simplified CFD setup and a simplified route simulation model. For each tested simplification, we find that they can be used under specific conditions, but not always. We give specific recommendations based on our results. To improve the predicted rudder resistance from the MMG model, we suggest a slightly modified model based on classical lifting line theory. All the numerical experiments are performed using the open source CFD library OpenFOAM. The simulation setup is described, including details of the mesh design. The numerical uncertainty is quantified, and the simulations are compared against benchmark experiments.