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Advances in Mathematical Physics
Volume 2012 (2012), Article ID 183503, 9 pages
http://dx.doi.org/10.1155/2012/183503
Research Article

Combination Mode of Internal Waves Generated by Surface Wave Propagating over Two Muddy Sea Beds

1Tainan Hydraulics Laboratory, Research Center of Ocean Environment and Technology, Tainan Hydraulics Laboratory, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan 701, Taiwan
2Department of Hydraulic and Ocean Engineering, Research Center of Ocean Environment and Technology, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan 701, Taiwan

Received 6 March 2012; Accepted 9 May 2012

Academic Editor: Sanith Wijesinghe

Copyright © 2012 Ray-Yeng Yang and Hwung Hweng Hwung. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

When surface wave propagating over the two layer system usually induces internal wave in three different modes: they are external, internal and combination. In the present study, the nonlinear response of an initially flat sea bed, with two muddy sections, to a monochromatic surface progressive wave was investigated. From this theoretical result, it shows that a surface water wave progressing over two different muddy sections, the surface wave will excite two opposite-traveling short interfacial waves, forming a nearly standing wave at the interface of the fresh water and the muddy layer. Meanwhile, two opposite-outgoing “mud” waves each with very long wavelength will be simultaneously induced at the interface of two muddy sections. As a result, the amplitudes of the two short internal waves are found to grow exponentially in time. Furthermore, it will be much difficult to excite the internal waves when surface water wave progressing over two muddy sections with the large density gap.