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This thesis proposes an improvement to present near-shore wave prediction models. Using weakly dispersive Boussinesq theory, the shoaling of directionally spread surface gravity waves over a beach with gentle gradients in the cross-shore and alongshore directions is examined. Following Herbers and Burton (1997), the governing fluid flow equations are expanded to third order and depth-integrated over the water column. A resulting amplitude evolution equation for a spectrum of waves is derived, which is the main result of this paper. New terms in the higher order result include effects due to alongshore bottom slope, higher order cross-shore depth variations, and non-linear quartet interactions. The linear terms in this equation are verified by analytical methods using linear finite depth theory. Example computations for a monochromatic wave train over a plane beach quantify some of the improvements of this result over the lower order model. Opportunities for further development and verification of this result are proposed, and recommendations for application of the result in its present form are outlined. / US Navy (USN) author

Global wave predictions produced at two U. S. forecasting centers, Fleet Numerical Meteorology and Oceanography Center and the National Centers for Environmental Prediction are evaluated with spectral buoy measurements. In this study, the fidelity of frequency-directional spectra predicted by WAM and WAVEWATCH III at the operational centers is examined with data from 3-meter discus and 6-meter nomad buoys operated by the National Data Buoy Center in the Atlantic and Pacific Oceans and Datawell Directional Waverider buoys deployed along the California coast by the Scripps Institution of Oceanography Coastal Data Information Program. Only buoys located in deep water are used in the comparisons. Model nowcasts of frequency spectra and mean wave directions are compared to buoy measurements over a six-month period from 1 October 2000 to 31 March 2001. At the Pacific buoy locations, individual swell events were identified in the spectra from the three models and the buoy data. Predicted and observed swell frequencies and arrival directions are compared as well as the total energy transported past the buoy over the duration of each individual event. At all buoy locations, predicted and observed wave energy fluxes integrated over fixed frequency ranges are compared. All three models yield reliable nowcasts of swell arrivals at the buoy locations. In most cases, the models under-predict the energy measured by the buoys. WAVEWATCH III better resolves low-frequency swells than WAM, possibly owing to a superior numerical scheme. Swell predictions at NCEP forced with AVN winds are more accurate than those at FNMOC forced with NOGAPS winds. / US Navy (USN) author

The shape of a liquid's surface is determined by both the body force and surface force of the liquid. In this report, the body force is solely from the gravitational force. The surface force is generated from the movement of an elastic interface between the solid and liquid. To obtain the shape of the surface, both asymptotic analysis and numerical approaches are used in this report. The asymptotic analysis is applied on the potential flow. The initial conditions are chosen to be the function of the shape of the interface between the solid and liquid and the free stream velocity far away from the interface. The time dependent contributions from the fluid system are also considered. The initial condition changes according to the function of the calculated velocity potential. The numerical approach includes two parts: calculation the velocity potential and a formalism of the change of the system as time evolves. For the first part, two idealized vertical boundaries are utilized to give a unique solution of the Laplace equation. The boundary conditions are determined as the flow under linear viscosity. For the second part, the flow is first assumed to be a potential flow, and a boundary layer is considered to make the no-slip condition valid and to give a more precise approximation for the shear stress.

by Chan Chi-kin. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

by Poon Lai Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 59-[64]). / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background of Measurement in Indoor Environment --- p.7 / Chapter 2.1 --- Propagation loss --- p.8 / Chapter 2.1.1 --- Basic concepts --- p.8 / Chapter 2.1.2 --- Indoor propagation --- p.13 / Chapter 2.2 --- Multipath characteristics --- p.15 / Chapter 3 --- Propagation Model --- p.17 / Chapter 4 --- Measurement Sites and Equipment Setup --- p.21 / Chapter 4.1 --- Measurement sites --- p.21 / Chapter 4.2 --- Equipment setup --- p.22 / Chapter 5 --- Measurement Results --- p.27 / Chapter 5.1 --- Propagation loss in the same building --- p.27 / Chapter 5.1.1 --- Measurement in Engineering Building --- p.27 / Chapter 5.1.2 --- Measurement in Hostel --- p.30 / Chapter 5.2 --- Penetration across the atrium and neighboring building --- p.31 / Chapter 5.3 --- Multipath characteristics --- p.33 / Chapter 6 --- Frequency Reuse Planning and Limitations on Measurement --- p.50 / Chapter 6.1 --- Frequency reuse planning --- p.50 / Chapter 6.2 --- Limitations on the propagation loss measurement --- p.53 / Chapter 6.3 --- Limitations on multipath measurement --- p.54 / Chapter 7 --- Conclusions --- p.55 / Appendix --- p.56 / Chapter A --- Method of Calculating Path Loss Slope --- p.56 / Bibliography --- p.59