Simulation dependency on degrees of freedom in rans solvers for predicting ship resistance

Abstract

At present days, CFD simulation is the mostly used tool at the design stage to investigate ship resistance in calm water and in waves. The common practice is to simulate ships with restricted degrees of freedom, instead of considering all the motions. However, in actual sea, ships maneuver with all degrees of freedom, and the impact of ignoring some motions in the simulation is not well discussed in existing literature. This paper investigates the influence of degrees of freedom in ship resistance simulation, using an in-house RaNS solver. The paper compares resistance and motion prediction results from simulations performed with different degrees of freedom, both in calm water and in waves. The paper concludes that the influence of some motions are higher in simulation comparing to others, and for resistance simulation, considering heave and pitch motion is sufficient.