| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 88 === Abstract
A numerical scheme was developed to solve the unsteady, two-dimensional Navier-Stokes equations and the exact free surface boundary conditions for investigating the bottom boundary layer flows induced by water waves. A piston-type wavemaker was set up in the computational domain to produce the incident waves, which include the small-, and the finite-amplitude waves as well as the solitary waves. The numerical results for the incident wave profiles and the velocity profiles from the bottom to the free surface have been shown to be consistent with the analytical and experimental data. After having verified the accuracy of the present numerical scheme, the effect of the Ursell number on the main characteristics of the boundary layer flows were systematically studied. These include the velocity profile within the boundary layer, the bottom shear stresses, the phase difference between the bottom shear stress and the wave profile, etc. The variation of the friction factor with respect to the Reynolds number was also discussed. Finally, the main characteristics of the boundary layer flow induced by a solitary wave was discussed in terms of the velocity profile, the temporal variation of the pressure and the bottom shear stresses.
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