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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/12166

Title: 三維數值L型多方向不規則造波機的開發
Development of Numerical 3D L-Type Multiple Directional Irregular Wave Generator
Authors: 周宗仁;石瑞祥
Contributors: NTOU:Department of Harbor and River Engineering
國立臺灣海洋大學:河海工程學系
Keywords: 三維數值水槽;L 型多方向不規則造波機;邊界元素法
Numerical 3D basin;L-type multiple directional irregular wave generator,Boundary element method;Quadrilateral element
Date: 2006-08
Issue Date: 2011-06-29T01:38:22Z
Publisher: 行政院國家科學委員會
Abstract: 摘要:利用數值水槽來做為解析各種波浪特性以及波浪與結構物間之各項水理特性之工 具,近年來已成為一個相當熱門的研究課題,開發各種數值水槽以分擔水工模型實驗之 龐大經費及場地問題已成為一未來趨勢。在考量水面為強非線性條件下,本人利用時間 領域之觀念完成三維多方向平面造波水槽的開發,對於三維多方向數值造波水槽之開發 研究已初步完成並有結果,成功的完成了規則波、不規則波及孤立波等之造波模擬,並 進行短峰波及大角度入射波之多方向造波數值模擬。由於造波板設置於解析領域內其中 一個邊界面,與真實實驗室之造波水槽相同,有其最佳之造波角度,其多方向不規則波 區有限,模型必須配置於其有效造波範圍內,故通常會較接近造波機,對於某些入射波 角度過大的計算例則僅部份模型區域有波浪通過,同時對於不規則波浪之模擬亦因受到 有限之造波區範圍而影響結果之精確度,同時模擬造波時間也因為模型較接近造波機, 受到地形、地物之反射波影響而縮短。為解決此問題,本人擬進一步探討並開發L 型( L -type )多方向不規則造波機之三維數值平面水槽。 本研究計畫擬以三年的時間完成此三維L 型多方向非線性造波機之數值模式,利用 邊界元素法以Lagrange 法描述流體運動,同時配合時間差分觀念來建立此,可解析三維 波浪之造波、傳遞與變形之問題,於虛擬造波邊介面導入各種造波條件,並可藉由此數 值模式來模擬實際造波水槽之各種造波問題,本文解析時將採用活塞推拉式造波機 (piston type wave generator)為造波機之型式,模擬活塞式造波機之造波過程,解析過 程並考量其自由水面之非線性條件。三維水槽的界面分割為許多微小的四邊形線形元素 ( quadrilateral elements ),利用邊界元素法解析邊界值問題。特異點利用保角映像法 (conformal mapping)來消除;幾何學上邊界的不連續時則利用三節點法(triple-node method)來解決不同邊界條件之共存問題,此三節點法乃由本人在解析二維造波問題時 所採用二節點法(double-node method)之延伸。另外在數值上所產生的誤差,將以節點 間距離平方之反比為權重加以平滑化,屆時會考慮多種平滑方式。 本研究將對L 型多方向不規則波波進行數值造波模擬,完成不同波浪型態在有地形 及地物之水槽中的造波模擬,可探討波浪之反射、繞射問題,波與波之交互作用問題, 並可用以預測港池遮蔽效應及其靜穩度。未來模擬結果並可透過可視化之作業,將複雜 的數值計算結果以動態之型態表現出來。可提供作為一般水工模型試驗之輔助工具,結 合理論與實際工程之應用,可預先模擬作為重大公共建設前置作業及決策之參考。
abstract:Developing of L-type multiple irregular wave generator to produce improving oblique planar wave train in the basin are studied in this investigation. Generally, numerical model as well as physical test have same problems in a multi directional wave basin using wave makers series in a line, the effective experiment area with uniform wave field is small, the reflected waves as well as the re-reflected waves from the landforms and/or model cannot be efficiently absorbed, therefore, in order to enlarge the effective experiment area, wave makers are set in L-shape. A numerical simulation of three-dimensional wave making problem of fully nonlinear water surface condition are considered by boundary element method with quadrilateral element. The numerical scheme was based on the Lagrangian description together with finite differencing of the time derivative. Though it is clear that paddle of any desire type can be simulated by substitute different wave motion conditions, a multidirectional piston wave generator is selected in this study. The singular points in mathematics and geometry, conformal mapping and triple-node method are applied respectively, several smoothing methods will be consider to smoothen the results. An algorithm to generate wave with any prescribed form was also implanted in this scheme. Generally speaking, studies of wave-wave and wave-structure interaction can be carried out physically in a wave tank together with numerical model field experiments; on the other hand, computer algorithms are widely used to study this problem numerically nowadays, and quite often, both these techniques rely heavily on computers, which eventually anticipate the consequences as consultation in the academia.
Relation: NSC95-2221-E019-075-MY3
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/12166
Appears in Collections:[河海工程學系] 研究計畫

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