| The focus of the research is the evaluation of dynamic and static pressures acting on floating bodies. Specifically, these pressures result from large motions of a multi-hull ship in 6 dof. The components of the dynamic pressure are radiation, diffraction, and the Froude-Kriloff pressures. Evaluation of instantaneous radiation and diffraction problems is always computationally expensive. Previously, many seakeeping analyses do not solve for the diffraction pressures explicitly.; A blended scheme is presented here for the evaluation of total hydrodynamic pressure. The method employs quasi-nonlinear radiation and diffraction models, and body exact hydrostatic and Froude-Kriloff pressures. The quasi-nonlinear radiation and diffraction pressures are estimated without solving the boundary value problems recursively, instead using a radial-basis function. The method is equally applicable to regular and irregular seas, in frequency and time domains. Direct integration of these pressures results in nonlinear displacements, other kinematics and the structural loads in terms of dynamic shear forces, bending and torsion moments in 6 dof. The nodal pressures are in an appropriate format for use in commercial software such as MAESTRO or other FEM based design tools. Nonlinearities arise from Euler angles, large motions and the exact instantaneous intersection of the body and free surface. For the forward speed corrections, ∂/∂x, is calculated by converting the two-dimensional velocity potential into a three-dimensional mathematical function via radial-basis functions. To restore two-dimensional characteristics of the boundary value solution, a backward conversion to two-dimensions is performed.; Good agreement is found between the blended method and experimental data for radiation and wave loads on a steadily moving vessel. To demonstrate the usefulness of the method, capsize basins and parametric roll studies were conducted. It is demonstrated that resonating roll excitation occurs for the given parametric conditions.; This thesis presents the use of radial-basis functions for estimation of quasi-nonlinear radiation and diffraction pressures and their conversion between two and three dimensions; as a result significant savings in computation-time are realized. |
