Determination of rotational damping coefficients of a heavy lift vessel using computational fluid dynamics (CFD)

Abstract

Heavy lift vessels are used for the transportation of heavy loads and the installation of offshore structures. These operations require a stable vessel and large operational windows. For the transportation of these heavy loads, roll motion is of utmost importance because of the possibility of green water ingress, loads on sea fastening, and submergence of the overhung parts of the cargo or cargo damage due to high accelerations caused by the roll motion. This study focuses on the determination of the total non-dimensional roll damping coefficients. The roll damping coefficients can be calculated using various techniques including the potential methods, semi-empirical methods, hybrid methods (potential + semi-empirical methods), model tests, or RANSE CFD. The potential solvers don’t take into account the viscous effects during the roll damping but other techniques are used to include these viscous effects in the potential solvers like hybrid methods. Semi-empirical methods like Ikeda Method has its limitations of slender hulls and barges which are not comparable to a heavy lift vessel, and also not including the interaction effect between different components of the roll damping. Model tests are usually expensive and provide a limitation of changes in geometry as well. RANSE-CFD is used in this study, to determine the total non-dimensional roll-damping coefficients accurately including the viscous effects.