A time domain strip theory approach to predict maneuvering in a seaway

A time-domain body exact strip theory is developed to predict maneuvering of a vessel in a seaway. A frame following the instantaneous position of the ship, by translating and rotating in the horizontal plane, is used to set up the Boundary Value Problem (BVP) for the perturbation potentials. Linearized free surface boundary conditions are used for stability and computational efficiency, and exact body boundary conditions are used to capture nonlinear effects. A nonlinear rigid body equation of motion solver is coupled to the hydrodynamic model to predict ship responses.;At each time-step, a two-dimensional mixed BVP is solved by using a boundary integral technique. Constant strength panels are used on the body surface and desingularised sources are placed above the free surface nodes. The constant strength panels have been shown to have better capability in handling complex hull geometries. The free surface and rigid body equations of motions are evolved in time using a fourth-order Adams-Bashforth technique. A separate BVP is set up to solve for the acceleration potential.;Forced oscillation problems are used to study convergence with respect to time-step size, number of body panels and free surface domain length. The seakeeping prediction capabilities of the method have been established by Bandyk (2009).;As a first stage of the research, the drifting of a ship freely floating without power in a seaway is simulated. Simulations are performed with and without viscous corrections, and give some interesting results. The Wigley-I and the containership S-175 are used for these studies. This is used to establish the robustness and stability of the code to perform long time simulations on the order of hundreds of wave periods.;The second stage of the thesis involves the prediction of controlled maneuvers of the containership S-175 in calm waters and in the presence of waves. The turning circle maneuver is performed on the S-175, and results compared with available experimental results. The simulations are able to capture general qualitative aspects and the essential physics of the problem. Computational issues are addressed in this chapter.;The third stage of the research involves the formulation of an empirical surge force model used in the methodology to correct the potential flow results. Comparisons are made with results obtained from open source CFD solver OpenFOAM.;The methodology has been shown to be robust, computationally efficient, and capable of predicting long time simulations of a ship maneuvering in a seaway. Although the basic physics of the problem are captured, the research is in a nascent stage, and computational issues are present. These are addressed wherever possible, and recommendations suggested. Also better models for external forces such as propeller thrust, rudder lift forces, and viscous modeling are required to improve the predictions of the method.