Unified approach to ship seakeeping and maneuvering by a RANSE method

In this work, a computational procedure for the prediction of motion of rigid bodies floating in viscous fluids and subjected to currents and waves is presented. The procedure is based on a coupled iterative solution of the equations of motion of a rigid body with up to six Degrees Of Freedom (DOF) and the Reynolds-Averaged Navier-Stokes Equations (RANSE) describing the turbulent fluid flow. The fluid flow is analyzed using a commercial CFD package (Comet) which can use moving grids made of arbitrary polyhedral cells and allows sliding interfaces between fixed and moving grid blocks. The computation of body motion is coupled to the CFD code via user-coding interfaces on the basis of each iteration. A fullyimplicit predictor-corrector procedure is employed for the calculation of body motion, taking advantage of the iterative nature of the fluid-flow solver. The method is used to compute the motion of floating bodies/ships subjected to waves, showing favorable agreement with experiments. Extension to more complex ship maneuvering applications is further conducted, which requires modeling of interaction of ship, its rudder(s) and its propeller(s). With the ship hull and the rudder modeled geometrically and the propeller simulated by a body force model, turning circle and Zigzag maneuvers are performed as examples and the comparison with measurements shows promising agreement.