A Study on the Hydrodynamic Interactions Between Demi-Hulls on Roll Damping of a Catamaran Type Crew Transfer Vessel Using RANS Simulations

Abstract This study investigates the roll damping characteristics of a catamaran-type Crew Transfer Vessel (CTV) through RANS-based forced roll simulations. Unlike previous research that has focused primarily on macroscopic measurements, this work examines both the catamaran as a whole and its individual demi-hulls, aiming to clarify the effect of hydrodynamic interactions on roll damping. The computational approach uses an overset-grid method and an in-house CFD solver, incorporating a level set method for free-surface capturing and an explicit algebraic stress model for turbulence representation. Simulations are conducted at model scale and consider various roll periods. Results indicate that hydrodynamic interactions between the demi-hulls significantly influence roll damping coefficients and lift components. Flow field analysis reveals increased fluid velocities between the demi-hulls and more complex wave patterns during forced roll motion, highlighting the importance of considering demi-hull interactions in design and analysis.