半圆型潜堤共振反射的数值与试验研究

发布时间：2018-06-16 13:24

本文选题：半圆型潜堤 + BEM数学模型　；参考：《中国海洋大学》2014年硕士论文

【摘要】：防波堤是常见的港口水工建筑物之一，主要功能有防浪、挡沙、导流、保护天然海岸线等作用，对于维持港口池内的水域平稳以及保护海岸结构有着重要的作用。作为防波堤的一种，潜堤被广泛应用，优化其结构、布置形式是一个重要的研究方面。本文对波浪通过半圆型系列潜堤时发生的共振反射现象（布拉格反射）进行了探讨，采用数值模拟与物理模型试验相结合的方法进行研究。数值计算方面是在势流理论的基础上，以简单格林函数为基本解，利用边界元方法（BEM）建立了数学模型；水槽试验采用规则波，进行了单列、双列半圆型潜堤的试验。双列半圆型潜堤采用两种试验形式，一种是固定波浪周期，不断改变潜堤间距，得到Kr~2S/L（Kr反射系数，S潜堤间距，L波长）曲线；另一种是固定潜堤间距，不断改变波浪周期，得到Kr~kh（Kr反射系数，k波数，h水深）曲线。根据采集的数据分析了潜堤个数（N）、潜堤半径（R）、潜堤间距（S）、波浪周期（T）和波浪破碎对半圆型潜堤的反射系数（Kr）及透射系数（Kt）的影响。通过数值计算与物理模型试验， Kr~2S/L曲线中主频共振反射周期性地出现，各峰值大致相同，且相同半径下各峰值间隔并不随着周期、波陡的变化而改变； Kr~kh曲线中，，主频共振反射的峰值位置随着潜堤间距的增加不断向周期较大的方向移动，同时共振反射的带宽逐渐变窄。半径R=0.4m的半圆型系列潜堤无论是多少列，在周期T=1.2s作用下都会发生几乎全透射现象，半圆型潜堤基本不起作用，在工程应用中应注意避免。在本文试验条件下，波浪通过半圆型潜堤的破碎形态介于卷破波与激散破波之间，波浪破碎对堤前的反射特性影响不大，共振反射规律明显。但是波浪破碎后产生的非线性因素等使得堤后透射波高变得非常复杂。
[Abstract]:Breakwater is one of the common port hydraulic structures, which has the main functions of wave prevention, sand blocking, diversion, protection of natural coastline and so on, which plays an important role in maintaining the stability of the water in the port pool and protecting the coastal structure. As a kind of breakwater, submersible embankment is widely used. It is an important research aspect to optimize its structure and layout. In this paper, the resonance reflection (Bragg reflection) of waves passing through a series of semi-circular submersible embankments is discussed, and the method of numerical simulation and physical model test is used to study the phenomenon. On the basis of the theory of potential flow, the mathematical model is established by using the boundary element method (BEMM) on the basis of the simple Green's function, and the experiment of single-row and double-row semi-circular submersible embankment is carried out by using regular waves in the flume test. The double-row semi-circular submersible embankment adopts two kinds of test forms, one is to fix wave period, and the distance between submersible dikes is changed constantly to get the Kr 2S / L Kr reflection coefficient and S submersible dike spacing (L wavelength) curve; the other is to fix the submersible dike spacing and constantly change the wave period. The Kr reflection coefficient (K wave number and water depth) curve is obtained. Based on the collected data, the effects of the number of submersible dikes, the radius of submersible dikes, the distance between submersible dikes, the wave periodic T) and the wave breakage on the reflection coefficients (K) and the transmission coefficients (Kt) of the semi-circular submersible dike are analyzed. Through numerical calculation and physical model test, the main frequency resonance reflection appears periodically in Krn 2s / L curve, each peak value is approximately the same, and the peak interval does not change with the period and the wave steepness at the same radius. With the increase of the distance between the submersible embankment, the peak position of the main frequency resonance reflection moves to the direction of larger period, and the bandwidth of the resonance reflection becomes narrower. No matter how many columns the semicircular submersible dike with radius R ~ (4) m, almost fully transmitted phenomenon will occur under the action of periodic T ~ (1.2) s, and the semi-circular submersible embankment has no effect, so attention should be paid to avoiding it in engineering application. Under the experimental conditions, the breakage of waves passing through the semi-circular submersible embankment is between the breaking wave and the exciting wave. The wave breakage has little effect on the reflection characteristics in front of the embankment, and the resonance reflection law is obvious. But the nonlinear factors such as wave breaking make the wave height behind the breakwater very complicated.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U656.2

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