二維有限推移式造波水槽之瞬時波動解析

Abstract

一些海岸工程的研究集中於特殊的單一波浪，或是一群指定如波高和週期等的 波浪所造成的安全影響，因此，推算水槽中的瞬時波浪對於這些問題來說是非常重 要的課題。在本研究將提出在有限長度水槽中，藉由週期振盪的推移式從靜止開始 造波的卡氏座標的解析解。這些解可清楚地說明推導每一個公式的物理意義。並且 在週期運動造波板之試驗驗證理論之正確性。解釋及預測在前波之傳遞之機制，本 研究另一個探討的主題為瞬時造波之前波之傳遞解析。當波浪達到穩定前會有一個 比穩定波高還大之波存在，此存在之原因亦為本研究之重點。孤立波以在一個非常 長的水槽中生成，而但在主波後有漫延 (trailing) 的波群出現，本研究欲提出短期 造波所形成孤立波之解析並和試驗結果比較。本研究結果除可應用至造波外，亦可 應用至長波形成之現象及機制說明。

In the shallow water waves perform like a train of independent individual waves. The dynamic properties of each individual wave become increasingly important to the problems of coastal engineering. It hence is required in experimental works to generate desired transient waves or long waves. A laboratory flume is generally finite in length. An analytical solution in Cartesian coordinates for transient waves from rest generated by a periodically oscillating piston-type wavemaker in a flume of finite length is proposed in this project. The proposed solution clearly elucidates the physical interpretation of each equation through the whole derivation. The validity of the proposed solution will be verified by experimental results that will be carried out in IHMT (Research center of harbor and marine technology). The mechanics of a wave front in the transient waves and of one large wave existed ahead the regular waves in sinusoidally oscillating wavemaker will be pointed out. The solitary wave actually can be generated in a very long flume in which wave groups trailing the main wave are unimportant. An application of the proposed method is made to generate a transient solitary wave in a finite flume by a generation equation proposed by Goring and Raichlen (1984). The proposed analysis can be applied to generating the transient waves in finite flume as well as to showing propagation of long waves generated by a sudden force.