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29 2007 11 Proceedings of the 29th Ocean Engineering Conference in Taiwan National Cheng Kung University, November 2007

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Experimental Study on the Effect of Varying Pycnocline Thickness on Internal Solitary Wave Evolution

Tien-Yu Lu Ming-Hung Cheng Te-Wang Lai Wei-Hung Wang Chen-Yuan Chen John R-C. Hsu*

*Professor, Department of Marine Environment and Engineering, National Sun Yat-sen University

ABSTRACT

Internal solitary waves (ISW) have been detected on the interface of a stratified water column in the ocean. It is believed that ISW could affect oil drilling operations, nutrient pumping, and acoustic signal obstruction. In the ocean, the thickness of a pycnocline is finite which differs with the theoretical assumption as being an ultra-thin layer. This paper reports the propagation of an ISW in various pycnocline thicknesses. Our experimental results show that, as the thickness of the pycnoline increases, the values of all the physical parameters (e.g. wave amplitude, phase speed, and wave energy) decreases. Their reduction rates were more significant in the case of small interface displacement (0=10cm) than that with large value of 0=15cm. On the other hand, the physical variables associated with a depression ISW are more significant than those in an elevation ISW.

Key words: psycnocline thickness; internal solitary wave; laboratory experiment

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NSC 95-2611-M-110 -008

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