發(fā)布時間：2018-06-08 01:41

  本文選題：海嘯 + 孤立波��； 參考：《上海交通大學》2015年碩士論文

【摘要】：海嘯是自然界破壞力極強的海洋災(zāi)害之一,主要是由海底強地震、外來隕石撞擊等所引發(fā)的。各種海嘯的誘因均伴隨有深海水體的劇烈垂向運動。在深海中海嘯波高雖然不大,但其能力集中并且傳播速度極快,在海嘯波傳至近岸時,往往由于水深急劇變淺,波高陡增,在海灣及港口內(nèi)引起海水的巨大波動或振蕩,巨浪沖上陸地,淹沒岸邊,摧毀建筑物,成為嚴重災(zāi)害,而其中海嘯波在海岸和陸地上的爬高是造成陸地上破壞最直接的方式。本文基于RANS方程、VOF方法以及修正的Goring造波方法建立了模擬活塞式推波板運動的二維數(shù)值波浪水槽,實現(xiàn)了孤立波爬高的數(shù)值模擬。利用運動物體動邊界模擬造波機推波板的運動,有效地實現(xiàn)了單孤立波以及不同波峰間距雙孤立波的造波方法。首先通過基本的算例驗證數(shù)值波浪水槽的可靠性,結(jié)果表明:改進的孤立波造波方法與目標波形吻合較好,多組不同相對波高的單孤立波爬高極值與現(xiàn)有的理論值和實驗值均較接近;雙孤立波直墻爬高數(shù)值計算結(jié)果表明雙孤立波在傳播過程中與實驗值基本一致,且具有較好的穩(wěn)定性,數(shù)值模擬的結(jié)果與實驗結(jié)果基本一致。在一定的地形條件下,海嘯波在近海傳播過程中有可能會演化成若干個孤立波組成的波列。為了了解多個孤立波波列對海岸結(jié)構(gòu)物的作用機理,在數(shù)值波浪水槽中進行了雙孤立波的斜坡爬高實驗。在復(fù)驗了孤立波直墻爬高的基礎(chǔ)上,設(shè)計了多種波高組合作為目標波形,根據(jù)所得數(shù)據(jù)進一步研究雙孤立波兩個爬高極值的變化規(guī)律,以及這些變化與入射波高和雙孤立波兩個波峰間相對距離的關(guān)系,同時針對等波高的雙孤立波,研究其速度場及能量轉(zhuǎn)化規(guī)律。數(shù)值模擬結(jié)果表明:對于等波高的雙孤立波,當入射波波高較大及兩個波峰間距相對較小時,跟隨在后孤立波的爬高放大系數(shù)小于先導孤立波的爬高放大系數(shù);雙孤立波在爬高過程中,波動場的勢能時間過程線呈現(xiàn)三峰形態(tài),其中居中的最大勢能峰值出現(xiàn)在第二個孤立波與經(jīng)斜坡反射后反向傳播的第一個孤立波完全對撞的時刻;同時在斜坡角度較小時,雙孤立波的一個孤立波動能完全轉(zhuǎn)化為勢能是先于該波在斜坡上爬到最高點,而斜坡角度增大至到直墻時,雙孤立波的一個孤立波動能完全轉(zhuǎn)化為勢能和該波在斜坡上爬到最高點是同一時刻。
[Abstract]:Tsunami is one of the most destructive marine disasters in nature, which is mainly caused by strong submarine earthquakes and impact of foreign meteorites. The causes of various tsunamis are accompanied by intense vertical motion of deep sea waters. Although the tsunami wave height is not large in the deep sea, its ability is concentrated and its propagation speed is extremely fast. When the tsunami wave reaches the shore, it often causes a huge fluctuation or oscillation of the sea water in the bay and port due to the sharp shallowness of the water depth and the sharp increase of the wave height. Huge waves have washed up the land, flooded the shore, destroyed buildings, and become a serious disaster, and the tsunami wave climbing on the shore and land is the most direct way to cause damage on the land. Based on the Rans equation and the modified Goring method, a two-dimensional numerical wave flume is established to simulate the motion of the piston plate. The numerical simulation of the solitary wave climbing is realized. In this paper, the moving boundary of moving object is used to simulate the motion of the wave plate of the wave-maker, and the method of generating single solitary wave and double solitary wave with different crest spacing is realized effectively. The reliability of numerical wave flume is verified by a basic example. The results show that the improved solitary wave generating method is in good agreement with the target waveform. The single solitary wave climbing extremum of several groups of different relative wave heights is close to the existing theoretical and experimental values, and the numerical results of double solitary wave vertical wall climbing show that the double solitary wave is basically consistent with the experimental value in the process of propagation. The numerical simulation results are in good agreement with the experimental results. Under certain topographic conditions, the tsunami wave may evolve into a series of solitary waves in the course of offshore propagation. In order to understand the action mechanism of several solitary wave trains on coastal structures, a slope climbing experiment of double solitary waves was carried out in a numerical wave tank. On the basis of the repeated inspection of the climbing of the straight wall of solitary waves, several wave height combinations are designed as the target waveforms. According to the obtained data, the variation law of the two climbing extremum of the double solitary waves is further studied. The relationship between these variations and the relative distance between two peaks of incident wave height and double solitary wave is also discussed. The velocity field and energy transformation law of double solitary wave with equal wave height are studied at the same time. The numerical simulation results show that when the incident wave height is large and the distance between the two peaks is relatively small, the magnification factor of the following solitary wave is smaller than that of the leading solitary wave. In the process of double solitary wave climbing, the time line of potential energy of the wave field presents three peaks, in which the middle maximum potential energy peak appears at the time when the second solitary wave completely collides with the first solitary wave propagating backward through the slope; At the same time, when the angle of the slope is small, an isolated wave of the double solitary wave can be completely converted into the potential energy when the wave climbs to the highest point on the slope before the wave, and the angle of the slope increases to the straight wall. An isolated wave of a double solitary wave can be converted into potential energy at the same time as the wave climbs to the highest point on the slope.
【學位授予單位】：上海交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P731.25

【參考文獻】

相關(guān)期刊論文 前1條

1 王永學;;VOF方法數(shù)模直墻式建筑物前的波浪破碎過程[J];自然科學進展;1993年06期

，

本文編號：1993807