Thesis (MScIng)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Meteorology. / Bibliography: leaf 34. / M.S.

This thesis consists of an experimental study of the velocity distribution in tranquil, stable tumbling and rapid flow regimes in a steep rectangular channel with artificial roughness elements. Four shapes of roughness elements, rectangular, parallelogram, triangular, and semi-circular, were used. Effects on velocity distribution due to variations in discharge, flume slope and roughness geometry were studied for each shape of roughness element. The applicability of logarithmic law was examined and the inflection points in tranquil and rapid flow regime were studied. Also the velocity coefficients in tumbling regime were studied. The findings were confirmed through the analysis of data taken from project 405 of the Civil Engineering Department. A review of literature on this subject and a bibliography are included. / Master of Science

Master of Science

A theoretical model and associated computer program are developed to compute hydrodynamic interaction forces and moments on passing ships in a shallow asymmetric canal, by applying generalized Lagally's theorem. Steady lift force on the ships are estimated following standard slenderbody approach. Passing ships are assumed to travel at constant speeds, parallel to the canal walls. Ships are assumed to be slender, the fluid is ideal and wave making effects are ignored. Numerical calculations for several passing cases show good agreement with existing model test results. / M.S.

The lift and drag forces exerting on a sphere immersed in a shear flow above a flat channel bed are evaluated by solving the steady three-dimensional Navier-Stokes equations. The numerical technique which combines the Newton iteration method and the finite element method is used to solve the non-linear Navier-Stokes equations. The technique first linearizes the non-linear terms in the partial differential equations, then solves the linearized equations by the finite element method. The Newton iteration method is used to linearize the non-linear equations. Since the iteration method requires a good initial guess, the linear solution of the partial differential equations is used for the initial guess, where the linear solution is the obtained by solving the differential equations without non-linear terms. The computer model developed can evaluate the lift coefficients of a sphere stationed at various distance from the channel bed. The computational results agree very well with the experimental measurements cited in the literature. The lift coefficient of the sphere changes with the undisturbed approaching velocity profile as well as the gap ratio which is the ratio of the distance between the sphere and the channel bed and the diameter of sphere. For fixed gap ratios, higher Reynolds number gives smaller lift coefficient than that of the lower Reynolds number. On the other hand, the lift coefficient also changes with the diameter of sphere for each fixed gap ratio. For small gap ratios, the lift coefficient increases as the diameter of sphere increases. For large gap ratios, the lift coefficient increases in the negative (downward) direction as the diameter of sphere increases. / Ph. D.

Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This work investigates methods to theoretically determine the lateral velocity distribution across a river from which factors may be derived to translate a single point velocity into average velocity for the river as a whole. A wide range of field data from vanous nvers was analysed. This produced over a hundred velocity distributions with which to compare theoretical distribution results. Four theoretical approaches were considered: the one-dimensional method (Manning's equation), a two-dimensional flow formula solved as an initial-value-problem, a two dimensional flow formula solved as a boundary-value-problem and an empirical method developed from energy principles. The one-dimensional and initial-value-problem approaches were unsuccessful. The boundary-value and empirical approach did however produce promising results. Surprisingly the analysis of the field data revealed patterns of similarity which could produce accurate results without the need of a theoretical approach. / AFRIKAANSE OPSOMMING: Metodes word ondersoek om teoreties 'n laterale snelheidsverspreiding oor 'n rivier te bepaal en sodoende 'n faktor te vind waarmee 'n gemete enkelpuntsnelheid in die rivier omgeskakel kan word na 'n gemiddelde snelheid vir die rivier in geheel. Vloeimeetdata van verskeie nviere IS geanaliseer. Sodoende is meer as 100 snelheidsverspreidings gegenereer waarmee die teorie vergelyk kon word. Vier teoretiese benaderings is gevolg: Manning se een-dimensionele vloeivergelyking, 'n twee dimensionele vloei-vergelyking opgelos met behulp van 'n beginwaarde, 'n twee dimensionele vloei-vergelyking opgelos met behulp van randwaardes, en 'n empiriese metode ontwikkel vanuit energie beginsels. Die een-dimensionele- en beginwaarde-benaderings was me suksesvol me. Die randwaarde- en empiriese benaderings het wel belowende resultate gelewer. Selfs verwerking van die gemete stroommetings het waardevolle inligting gelewer: daar bestaan duidelike ooreenkomste in die snelheidsverspreidings wat gebruik kan word om die verspreidingsfaktor mee te bereken sonder om teoretiese oplossings te soek.

Durban is the busiest container port in Africa and there are plans for significant expansion during the next few years. This expansion includes the widening of the port entrance channel to accommodate larger "post-panamax" vessels. Complex crosscurrents near the port entrance, coupled with severe wind and wave conditions, may lead to the intermittent closure of the port which in turn could lead to significant economic implications. Information on the nature of the crosscurrents and how they affect the ships could assist harbour pilots in developing their skills and reduce the risks associated with steering ships into the port. The research involved a case study to develop an innovative new method for directly measuring the effect of wind, waves and crosscurrents on ships entering the port. The technology is based on the application of digital image processing to track the position of ships as they manoeuvre in the port approach channel. The key innovation of this research is the extraction of the heading direction of the ship from the image data. The angle between this heading direction and the true velocity vector (the "crab angle") is then a direct measure of the cross-track drift velocity (CTDV) due to the combined effects of wind, waves and currents. The crosscurrents are usually the main contributing factor to the cross-track drift. The aim of this research was to develop a fully automated image processing system for real-time ship monitoring, and to determine cross-track drift within a wide range of weather conditions and ship parameters. The methodology presented in this research allows the spatial structure of the CTDV along the harbour approach channel to be studied. The relationship of the CTDV to local surface winds was analysed. For deep draught vessels, measured CTDVs were found to be poorly correlated to surface winds. The spatial structure of the measured CTDVs shows distinct regions along the approach channel where vessels experience significantly larger drift velocities. In summary, with the software tools developed by this research, digital images can be captured automatically and analysed to produce ship tracks and crab angles. From this information an extensive database for ship manoeuvring in the approach channel can be developed and the safety and efficiency of port operations improved. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.

Thesis (M.Sc. (Civil Engineering)--University of the Witwatersrand, Faculty of Engineering, 1992.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.