Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Supervised by Carl Wunsch. Vita. Includes bibliographical references (leaves 203-209).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1980. / Supervised by Carl Wunsch. Vita. Includes bibliographical references (leaves 196-201).

Seabed stability in the vicinity of those offshore structure, which has been one of the particular concerns in engineering practice, can be compromised by the action of energetic waves. This project investigates the mechanisms of wave-induced soil response and liquefaction in a porous seabed near offshore structures. For this purpose both 2-Dimensional (2-D) and 3-Dimensional (3-D) integrated Wave-Seabed-Structure Interaction (WSSI) models have been developed within the project. They were used to simulate the effect of nonlinear wave-structure interaction on dynamic soil response in the neighbourhood of offshore pipelines, mono-pile structures, and multi-cylinder structures. Prior to applying the proposed WSSI models to practical engineering cases, several validations, mainly including wave and soil validations, were conducted. Excellent agreements between numerical and experimental results indicate the capacity of proposed WSSI models to simulate nonlinear wave-induced seabed response around offshore structures. Hereafter, the verified WSSI models are adopted to explore the mechanism of storm wave-induced soil response near offshore structures. The study of the offshore pipeline partially or fully buried in the seabed has shown that the leewake vortex can be sufficiently avoided with enough embedment, which also leads to lower possibility of the onset of scour in adjacent area of pipeline and the reduction of possible momentary liquefaction depth under pipeline bottom. Nonlinear wave-induced seabed response around a mono-pile structure, was investigated using the 3-D WSSI model developed in OpenFOAM, which allows to run numerical WSSI simulations in parallel. It was shown that, for waves propagating in a given longitudinal direction, the liquefaction occurs with greater depth at the lateral sides of mono-pile structure than at the front and back sides of mono-pile structure. Increasing penetration depth of the mono-pile structure slightly reduces the adjacent liquefaction depth. By adopting the same 3-D WSSI model, the numerical investigation of wave-induced soil response in the proximity of a multi-cylinder structure has been conducted. As found in the analysis by using same wave parameters in the case of a mono-pile structure, the nonlinear interaction between waves and multi-cylinder structure may significantly alter the distribution of liquefaction depth around each cylinder, compared to that for a single cylinder. Moreover, considering the effect of incident wave angles, such as 0° and 45° wave headings, it can be noted that the downstream cylinders are better protected from liquefaction threat due to the presence of upstream cylinders.

This study looks at the fluid interactions from the wake of a sail boat performing the heaving-to storm tactic in heavy weather seas with the waves. This interaction causes the wave height in the wake to be reduced. The fluid flow in the top layer of the wave is seen to move with the wake as the hull drifts with the wind. This movement of the top layer of the wave provides a vertical momentum cancelation affect with the portion of the wave that it moves over reducing the wave height. STAR-CCM+ CFD software is used to perform the simulations of the steep waves with wavelength of 25 meters, 55 meters, and 67 meters. In the simulation, a propulsive force is used to simulate the wind force on the boat. / Master of Science

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1980. / Microfiche copy available in Archives and Science. / Vita. / Includes bibliographical references. / by William Allan Perrie. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1980. / Microfiche copy available in Archives and Science. / Bibliography: leaves 77-78. / by William Kurt Dewar. / M.S.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Vita. / Bibliography: leaves 169-174. / Ph.D.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 241-244. / by Dale B. Haidvogel. / Ph.D.

Thesis: Sc. D., Massachusetts Institute of Technology, Department of Civil Engineering, 1980 / Bibliography: leaves 173-175. / by David William Ostendorf. / Sc. D. / Sc. D. Massachusetts Institute of Technology, Department of Civil Engineering

This investigation is concerned with the determination of the sea state in terms of wave spectra. The phenomenon was calculated for two different bathymetries. The purpose is to develop a finite difference method with an upwind differencing scheme to g solve several formulations of the wave action conservation equation. The computations were done in the wave number space and the frequency direction space. For the case of a beach with constant slope the results were compared with the analytical solution. For the case of an elliptical submerged shoal, they were compared with experimental data. The results of the computer code showed a fairly good qualitative agreement with the actual values for a smooth distribution of input energy. / Master of Science