【摘要】：海洋內(nèi)波分布范圍廣、形式多樣,其研究具有重要的工程價值和學(xué)術(shù)價值。在開發(fā)海洋資源的同時,海洋分層效應(yīng)已越來越成為不可忽略的重要因素。本文基于兩層流體的簡化模型,對層化海洋環(huán)境下二維結(jié)構(gòu)物的水動力特性進行了數(shù)值模擬研究。為了可以推廣到研究復(fù)雜海洋結(jié)構(gòu),采用外域級數(shù)展開和內(nèi)域邊界元數(shù)值方法相結(jié)合的手段建立了頻域數(shù)學(xué)模型,在外域和內(nèi)域交界的輻射面上利用連續(xù)性條件建立聯(lián)立方程組。邊界元方法可以將問題降維處理,只需要在域表面劃分網(wǎng)格,減少了計算量。同時內(nèi)域計算采用Rankine源作為格林函數(shù),既避免了求解復(fù)雜的格林函數(shù),又可直接獲得自由水面及內(nèi)界面上的速度勢。外域采用級數(shù)展開的解析式表達,將輻射面上速度勢的求解轉(zhuǎn)化為求解解析式中的待定系數(shù)。經(jīng)過與級數(shù)展開的解析方法對比,以及兩層流中波能流守恒的驗證,證明了本文建立的這一聯(lián)合數(shù)值模型的正確性。為了研究兩層流中存在結(jié)構(gòu)物時表面波模態(tài)和內(nèi)波模態(tài)波浪的轉(zhuǎn)化情況,定義了兩層流中各模態(tài)波浪的反射和透射系數(shù),利用這一數(shù)值模型通過計算反射系數(shù)和透射系數(shù)的變化情況,分析了兩層流中結(jié)構(gòu)物的反射和透射特性。研究了上下層密度比、水深比等層化參數(shù)對反、透射系數(shù)的影響。發(fā)現(xiàn)兩層流體密度差小時,內(nèi)界面很容易受到擾動產(chǎn)生大幅振動。計算并分析了兩層流中結(jié)構(gòu)物的附加質(zhì)量和輻射阻尼,給出了結(jié)構(gòu)物作強迫振蕩時,自由水面和內(nèi)界面的波面升高情況。最后,分析研究了結(jié)構(gòu)物分別在表面波模態(tài)和內(nèi)波模態(tài)波浪入射時的運動響應(yīng)問題。研究發(fā)現(xiàn),兩層流中內(nèi)波模態(tài)波浪入射時,結(jié)構(gòu)物運動響應(yīng)受層化參數(shù)變化的影響較明顯。
[Abstract]:The research of ocean internal wave has important engineering value and academic value because of its wide range of distribution and various forms. At the same time, ocean stratification effect has become an important factor that can not be ignored. Based on the simplified two-layer fluid model, the hydrodynamic characteristics of two-dimensional structures in stratified marine environment are numerically simulated in this paper. In order to extend to the study of complex ocean structures, a frequency-domain mathematical model is established by combining the outer domain series expansion with the internal domain boundary element numerical method. The simultaneous equations are established by using the continuity condition on the radiation surface at the boundary between the outer and inner domains. The boundary element method can reduce the dimension of the problem, only need to mesh the surface of the domain, and reduce the computational complexity. At the same time, the Rankine source is used as the Green's function in the inner domain calculation, which avoids solving the complex Green's function and directly obtains the velocity potential on the free water surface and the inner interface. The solution of velocity potential on the radiation surface is transformed into the undetermined coefficient in the solution of the analytic formula by using the analytic expression of the series expansion in the outer domain. The validity of the proposed joint numerical model is proved by comparing the analytical method with the series expansion and verifying the conservation of the wave energy flow in the two-layer flow. In order to study the transformation of surface wave mode and internal wave mode wave in the presence of structure in two-layer flow, the reflection and transmission coefficients of each mode wave in two-layer flow are defined. By using this numerical model, the reflection and transmission characteristics of structures in two-layer flow are analyzed by calculating the variation of reflection and transmission coefficients. The effects of stratification parameters such as the upper and lower layer density ratio and the water depth ratio on the inversion and transmission coefficient are studied. It is found that when the density of the two layers of fluid is small, the inner interface is easily disturbed to produce large vibration. The additional mass and radiation damping of the structure in two laminar flow are calculated and analyzed. The rise of the wave surface of the free water surface and the inner interface is given when the structure is forced to oscillate. Finally, the motion response of the structure under the surface wave mode and the internal wave mode is analyzed. It is found that the dynamic response of the structure is obviously affected by the variation of the stratification parameters when the internal wave mode is incident into the two-layer flow.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P75;P731.2

【參考文獻】

相關(guān)期刊論文 前2條

1 尤云祥,繆國平,程建生,朱仁傳;兩層流體中水波在垂直薄板上的反射與透射[J];力學(xué)學(xué)報;2005年05期

2 尤云祥;石強;魏崗;繆國平;;兩層流體中水波與垂直圓柱浮體的相互作用[J];上海交通大學(xué)學(xué)報;2007年09期

相關(guān)博士學(xué)位論文 前1條

1 劉進忠;淺海內(nèi)波引起聲場起伏的規(guī)律研究[D];中國海洋大學(xué);2004年

，

本文編號：2173742