【摘要】：海洋內(nèi)波是海水密度穩(wěn)定層結(jié)的海洋中普遍存在的現(xiàn)象，是海洋中大尺度能量級(jí)向小尺度能量級(jí)傳遞的中間過(guò)程，內(nèi)波的傳播演化具有研究意義。內(nèi)波的實(shí)驗(yàn)室研究可以整體全面的把握住內(nèi)波生成、演化的過(guò)程，同時(shí)可對(duì)理論研究與數(shù)值研究的結(jié)果進(jìn)行驗(yàn)證，而且實(shí)驗(yàn)室研究具有可重復(fù)性，相比海洋觀測(cè)而言資金投入少。 內(nèi)波的實(shí)驗(yàn)室研究之前需要制備密度層結(jié)的流體，，對(duì)于內(nèi)潮的實(shí)驗(yàn)需要在連續(xù)層結(jié)的流體中進(jìn)行。密度連續(xù)分層的流體通常采用雙缸法制備。采用傳統(tǒng)的雙缸法只能制備密度均勻?qū)咏Y(jié)的流體，而實(shí)際海水的密度剖面是具有躍層形式的。為了研究?jī)?nèi)波在非均勻?qū)咏Y(jié)下的傳播特性，作者改進(jìn)了傳統(tǒng)的雙缸法，從而可以制備出任意密度剖面的層結(jié)流體。經(jīng)實(shí)驗(yàn)驗(yàn)證這種改進(jìn)后的雙缸法具有可行性。 作者通過(guò)采用這種方法研究了內(nèi)波在不同密度層結(jié)下內(nèi)波射線的傳播現(xiàn)象。采用PIV技術(shù)對(duì)內(nèi)波射線的流場(chǎng)進(jìn)行觀測(cè)，采用合成紋影技術(shù)對(duì)內(nèi)波流體的密度擾動(dòng)進(jìn)行觀測(cè)。由線性內(nèi)波理論可知內(nèi)波群速與相速方向相互垂直，結(jié)合實(shí)驗(yàn)結(jié)果，可知實(shí)驗(yàn)結(jié)果中的射線即為內(nèi)波群速方向。根據(jù)內(nèi)波生成源（振蕩圓柱）的振蕩頻率與流體的浮性頻率N計(jì)算得到的群速與水平方向的理論夾角，與實(shí)驗(yàn)結(jié)果的所測(cè)得的角度進(jìn)行比較，發(fā)現(xiàn)兩個(gè)角度非常接近，說(shuō)明線性理論在本次實(shí)驗(yàn)的條件下是適用的。在三層線性分層實(shí)驗(yàn)中，內(nèi)波射線在不同層的界面處發(fā)生折射現(xiàn)象，同時(shí)在界面處也會(huì)發(fā)生內(nèi)波射線的反射現(xiàn)象。當(dāng)內(nèi)波圓頻率介于上下層的浮性頻率與中間層的浮性頻率之間時(shí)，內(nèi)波射線只在中間層傳播。向上向下傳播的兩條射線相互作用在第二次反射的位置處形成了一個(gè)渦旋，此渦旋不斷地生成、移動(dòng)并消失。 作者在水槽中加入斜坡地形，研究?jī)?nèi)波射線遇到斜坡地形后的反射。實(shí)驗(yàn)中發(fā)現(xiàn)在本次實(shí)驗(yàn)設(shè)置的情況下，內(nèi)波射線在反射后其寬度變窄。由于反射后的射線能量聚焦，內(nèi)波的能量損耗較強(qiáng)。 在測(cè)量?jī)?nèi)孤立波過(guò)地形后能量損耗的實(shí)驗(yàn)中，作者推導(dǎo)得到在實(shí)驗(yàn)室情況下計(jì)算內(nèi)孤立波動(dòng)能和有效勢(shì)能的方法，并通過(guò)實(shí)驗(yàn)測(cè)量了內(nèi)孤立波通過(guò)周期地形后的能量損耗率與其振幅之間大致呈線性關(guān)系。
[Abstract]:Ocean internal wave is a common phenomenon in the ocean with stable sea density. It is an intermediate process between large scale energy level and small scale energy level. The propagation and evolution of internal wave is of great significance. The laboratory study of internal wave can grasp the process of internal wave generation and evolution, and verify the results of theoretical and numerical research, and the laboratory research is repeatable. Less money is invested than ocean observation. It is necessary to prepare dense stratified fluid before the laboratory study of internal wave, and the experiment of internal tide should be carried out in the fluid of continuous stratification. Fluid with continuous density stratification is usually prepared by two-cylinder method. The conventional two-cylinder method can only produce homogeneous stratified fluid with density, while the density profile of the actual seawater is in the form of cline. In order to study the propagation characteristics of internal waves in non-uniform layers, the author has improved the traditional two-cylinder method, thus the stratified fluid with arbitrary density profile can be prepared. The experimental results show that the improved two-cylinder method is feasible. By using this method, the phenomenon of internal wave ray propagation under different density layers is studied. The PIV technique is used to observe the internal wave ray flow field and the synthetic schlieren technique is used to observe the density disturbance of the internal wave fluid. The linear internal wave theory shows that the direction of group velocity and phase velocity are perpendicular to each other. Combined with the experimental results, the ray in the experimental results is known as the direction of group velocity of internal wave. According to the theoretical angle of group velocity and horizontal direction calculated from the oscillating frequency of the internal wave generator (oscillating cylinder) and the floating frequency of the fluid, it is found that the two angles are very close to each other. It shows that the linear theory is applicable under the condition of this experiment. In the three-layer linear delamination experiment, the internal wave ray refraction occurs at the interface of different layers, and the reflection of the internal wave ray also occurs at the interface. When the frequency of the inner wave circle is between the floating frequency of the upper and lower layer and the floating frequency of the middle layer, the internal wave ray propagates only in the middle layer. The interaction of two rays propagating upward and downward forms a vortex at the position of the second reflection, which continuously generates, moves and disappears. In this paper, slope topography is added to the flume to study the reflection of internal wave rays upon the slope topography. It is found in the experiment that the width of the internal wave ray becomes narrower after reflection. The energy loss of the internal wave is stronger because of the reflected ray energy focusing. In the experiment of measuring the internal solitary wave energy loss after crossing the terrain, the author derives the method of calculating the internal solitary wave energy and the effective potential energy in the laboratory case. The linear relationship between the energy loss rate and the amplitude of the internal solitary wave after passing through the periodic terrain is measured experimentally.
【學(xué)位授予單位】：中國(guó)海洋大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P731.24

【參考文獻(xiàn)】

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本文編號(hào)：2201330