| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 91 === This thesis investigated the propagation of a solitary wave in river bends by solving the generalized Boussinesq equations (Wu, 1981) in the curvilinear coordinates. The objective is to study effects of the channel width, the bending directions and the flow speed on the transmitted long waves with channel flow over the bend. The experimental data by Yen (1965) is used to validate the numerical model. The numerical methods in use is of the second-order accuracy of central differences and time-averaged scheme with the upwind treatment in convection terms, algebraic grid generation and iterative LSOR technique for seeking time accuracy solutions. In order to obtain the optimal grid size the author considered the evolution of a solitary wave propagating into a straight water channel of uniform depth in later application, by means of the accuracy and efficiency of a numerical solution. The suggest grid size is then applied for the present study of the wave-flow interaction in a channel bend.
The numerical results show that, during a solitary wave traveling through the narrower channels, the transmitted wave crest turns radially straight and inclines higher outward against the outside wall with the wave amplitude changed smaller than 1%, and the longitudinal fluid velocity decreases almost inversely with local radius in the transverse section of the bends. During a solitary wave passing through the wider bend channels, the phase delay and super elevation on the waveform between the internal and external walls is more significant than those of the narrower channels. The transmitted wave takes more time to evolve into a final plane solitary wave. Furthermore, the initial wave disintegrated into several smaller waves because of the lateral reflection form the outside wall in the bends, so that the transmitted wave no longer holds the original shape（wave amplitude becomes smaller when the channel width is extending）.
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