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標題: | 三維海洋音傳與海床沙丘效應之研究 Three Dimensional Underwater Acoustic Propagation in Continental Slope Regions with Sand Dunes in South China Sea |
作者: | Meng-Chu Liu 劉孟竺 |
指導教授: | 陳琪芳(Chi-Fang Chen) |
關鍵字: | 水下音傳,方位角耦合,三維擾動效應,水中沙丘,FOR3DW, underwater acoustic propagation,θ-coupling,three-dimensional effect,underwater sand dune,FOR3DW, |
出版年 : | 2014 |
學位: | 碩士 |
摘要: | 在中國南海北部大陸坡上,有許多水中沙丘分佈在160公尺到600公尺水深,這些沙丘振幅最大可高達16公尺,導致在此海域的水下音傳會受到沙丘地形之影響,產生三維擾動效應。由於此海域的地形多變,若以二維的數值模擬(r,z)作計算,將會忽略水平方向的變化造成耦合效應(θ-coupling)消失,將無法完整描述其所造成的三維效應,因此模擬部分使用以三維拋物線方程式(parabolic equation)為基礎的三維數值模式(FOR3DW,圓柱座標模式,寬角度模式)進行模擬。本研究將利用正弦方程式(sinusoidal function)建立沙丘模式分析沙丘在不同振幅、波峰間距與沙丘走向造成的三維效應,並配合本團隊在2013年於此海域所獲得相關實驗資料進行聲學模擬比對,分別以二維、三維傳播模式探討,分析南海沙丘對水下聲音傳遞所造成的三維擾動效應,進一步了解沙丘之聲學特性,且利用本團隊蒐集之地形資料藉以規劃各聲學儀器佈放位置與深度。 There are many underwater sand dunes in the upper continental slope at the depth of 160m to 600m in northern South China Sea. These sand dunes are special as they are the largest sand dunes observed with amplitude up to 16m. Underwater acoustics transmission will be affected by these sand dunes and in turn produce the three dimensional effects. Due to the variation of topography in this area, if we use the 2-D (r,z) model, it will ignore the variation of horizontal direction and cause the θ-coupling disappear, causing us unable to describe the three-dimensional effects of the sand dunes completely. So, the 3-D underwater acoustic propagation model, FOR3DW (based on the cylindrical coordinates, the wide-angle version of FOR3D) is used to analyze the 3D effects caused by the sand dunes in South China Sea. In order to identify the causes generating 3D effects, ideal sinusoidal topography of different amplitudes, crest-to-crest intervals, and angles between the propagation direction and the orientation of dunes are studied. Then the actual environmental inputs from the experimental sites in the northern South China Sea are used to do the 3D calculations, which are used to plan for 3D acoustic propagation in the experiment conducted in June 2014. The 3D simulation is compared with the experimental data. Good match of data and simulation are found in some periods, while there are discrepancies in other time which demands future investigation. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55821 |
全文授權: | 有償授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
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