Computation of hydrodynamic coefficients and determination of dynamic stability characteristics of an underwater vehicle including free surface effects

The inviscid hydrodynamic coefficients of an underwater vehicle (Ocean EXplorer), including the nonlinear effects of the wave surface, are computed using a boundary-integral method. A mixed Eulerian-Lagrangian formulation (Longuet-Higgins and Cokelet, 1976) is used for the treatment of nonlinear free-surface conditions. The algorithm is validated using the work-energy theorem (Yeung, 1982) and experimental data. Results, in the form of free-surface elevations and hydrodynamic coefficients, are obtained for a range of body geometries and maneuvers. The open-loop dynamics of underwater vehicles are then investigated by solving the 3DOF rigid-body equations of motion (OXY plane). The advantages and possible usage of the developed methodology for the design and control of underwater vehicles, as well as topics for further research, are addressed in the conclusion chapter of the thesis.