URANS V&V for KCS free running course keeping and maneuvering simulations in calm water and regular head/oblique waves

The capability of CFD is assessed by utilizing CFDShip-Iowa V4.5 for the prediction of the 6DOF motion responses, forces, moments and the local flow field of the 2.7m KCS model in various weather/operating conditions. The discretized propeller is preferred and the rudder is designed to be active up to ±35 degrees. Grid triplets are generated with the refinement ratio √2 and verification is achieved for the resistance and propeller open water tests while for the other tests is only partially fulfilled. The verification shows unsmooth convergence, however, the errors from grid triplets are small. The propeller open water test validates the performance of the discretized propeller successfully. The free decay tests could predict reasonable heave/pitch/roll natural frequencies. The resistance test verifies the nominal wake distribution. The self-propulsion test using discretized propeller shows 18% higher propeller inflow and 0.1 thrust deduction factor compared to resistance test. A propeller blade that sweeps the starboard experienced higher thrust inducing non-axisymmetric propeller wake and thus affecting the angle of attack of the rudder. Neutral rudder angle diminishes effective angle of attack and keeps the course straight. Maneuvering simulations could predict qualitatively good agreement for validation variables while the trajectory needs more improvement. Using the discretized propeller for the head/oblique wave course-keeping simulations achieved validation successfully. The RAO of added thrust, torque and propeller rotational speed resembles the RAO of added-resistance except showing larger values during long waves. The mean propeller efficiency is at the minimum when the ship experiences a resonance. The first harmonic amplitude of the propeller efficiency increases followed by the increase of the wavelength.