Numerical Study of Generalized Interfacial Solitary Waves

• Main Authors: Chih-Feng Ni, 倪芝鳳
• Other Authors: Tian-Shiang Yang
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/22366216927865899405

碩士 === 國立成功大學 === 機械工程學系 === 89 === In a two-layer fluid system where the lower fluid is bounded below by a rigid bottom and the upper fluid is bounded above by a free surface, two kinds of solitary waves can propagate along the interface and the free surface. They are classical solitary waves characterized by a solitary pulse and generalized solitary waves with in addition nondecaying oscillations in their tails. In this thesis, we carry out a numerical study of generalized gravity solitary waves in a two-layer fluid system. The solutions depend on four dimensionless parameters, the layer thickness ratio, the density ratio, the Froude number, and the phase shift of the tail oscillations relative to the main solitary-wave peak. When the phase shift is varied while the other three parameters are kept fixed, our numerical results indicate that there exist two limiting cases. At a particular phase shift, the amplitude of oscillations reaches a minimum value, which is exponentially small but generally nonzero. On the other hand, at another particular phase shift that differs the previous one by about , the amplitude of oscillations increases drastically, in which case the generalized solitary wave eventually becomes a periodic wave. Also, generally speaking, the amplitudes of the solitary pulse in the central part and the far-field oscillations grow with increasing Froude number.