Forced roll simulations and ship roll damping computations using URANS

Ship roll response and associated roll damping estimation have long been an area of research, due to their detrimental nature to ship safety and habitability, and owing to the challenging roll damping computations that remain vague because of difficulties arising from strong viscous effects typical of ship roll motion. This work presents an assessment of roll damping of S175 container ship by performing Unsteady RANS simulations on CFD tool FLUENT, hence inherently incorporating viscous effects. The simulations consist of forced roll tests similar to that performed in model tests. Bilge Keel, roll amplitude (particularly large amplitude rolling) and roll frequency effects on roll response are considered. Vortex shedding is captured through simulations; besides the manuscript delineates the effects of frequency, roll amplitude and bilge keel on vortex formation and roll damping. Numerical verification and validation is accomplished. Comparison with experimental results is overall satisfactory.