【作者】 林玉芳；

【导师】 张宁川；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2012， 硕士

【摘要】 水平板类防波堤消防浪效果和波浪荷载受诸多因素影响,已有研究表明双层板较单层或多层板具有其优势并对消除波浪有确实效果。对双层水平板防波堤,多设为潜淹没型式。现有成果缺乏波浪荷载变化规律的系统分析,特别是深层次的消浪机理和实用化尺度优化研究更少见。针对上述问题,本文采用物理模型试验与数值模拟相结合的方法研究了浅淹没双型双层水平板防波堤的水动力特性。数值模型研究部分,利用Fluent软件,基于考虑真实流体粘性的N-S方程,结合Fluent中用户自定义函数(UDF)功能在连续方程和动量方程中分别添加造波源项和消波源项。利用采用VOF方法捕捉自由面,建立了二维数值波浪模型。该模型可同步获得水平板上的波浪压力、水平板周围的流场及水平板前后的波浪形态。物理模型试验部分,直接测定了双层板结构各表面上点压力分布,为数学模型的验证提供论证依据。基于通过验证的数值模型,通过较大范围地变化多个影响因素的取值范围,考察不同影响因素对双层水平板型防波堤荷载的影响,进而获得双层水平板型防波堤荷载的变化规律；通过流场结构、波浪压力分布的联合分析较深层次地探讨消浪和受力机理。研究主要结论归纳为：1.相对板宽B/L和相对水深d/L对是影响浅淹没型双层水平板防波堤防浪性能两个最重要的参数,而相对板间距S/H影响较小。2.就相对板宽B/L而言,对于单频波浪,不是板越宽消浪效果越好,而是消浪效果随板宽的增加(相对板宽在0.3～1.5范围内变化时)呈现波动。当相对潜深d1/H在0.4～1.33、相对板间距S/H在1.0～1.67范围内变化时,B/L取值为0.8～0.9时防波堤防浪效果最佳。3.就相对水深d/L而言,相对水深越小,双层水平板的消浪效果越佳。在相对潜深d1/H在0.4～1.33、相对板宽B/L在0.284～0.67范围内变化时,相对水深小于0.2时,透射系数不大于0.4；相对水深在0.2～0.3范围内变化时,透射系数在0.4～0.7范围内变化。4.上层板所受总力与双层板所受总力大小相当,且随相对板宽B/L、相对板间距S/H和相对水深d/L的变化趋势基本一致；下层板所受结构总力较小。5.双层水平板的消浪机理之一可以认为是双层板阻断了波浪的正常行进,将波浪水质点的准闭合椭圆运动分隔转变成多层复杂运动形态,在双层板中间水域,主要以板后方波浪的回流为主,水质点呈水平运动；在水平板两端和结构物上方,强紊动和漩涡运动为主；在水平板下侧,也以水平运动为主。上述流场结构具有能量耗散、反射作用,进而起到减小结构物后方波浪波高的作用。6.行进波浪与回流波浪的碰撞是产生结构物表面冲击压力的主要因素。上层板上表面前端和后端最容易受到冲击压力的影响。更多还原

【Abstract】 The wave-dissipating performance and wave forces of horizontal plate breakwater are influenced by many factors. Existing research has revealed that compared with single plate breakwater and multi-plate breakwater, twin-plate breakwater has better wave-dissipating performance, and most of the win-plate breakwaters are designed as shallow submerged type. However, existing research achievement lacks of systematic analysis of the varying pattern of wave forces, especially for the research of deep wave-dissipating mechanism and practical scale optimization.In view of the above questions, this dissertation conducts a series of studies related to the hydrodynamic performance of shallow submerged horizontal twin-plate breakwater through both physical model tests and numerical simulation.As for numerical simulation, a2-D numerical wave flume is developed based on FLUENT software.2-D Reynolds-Averaged Navier-Stokes equation, which considers real viscosity, is used together with the UDF function of Fluent. The wave generation source and wave-dissipating source are added in the continuity equation and momentum equation. The VOF method is used to capture free surface. This numerical model can be used to obtain wave pressure on the horizontal plates, wave particle velocity around the breakwater and waveform at the front and back of the breakwater.As for the physical test, wave pressure on the surface of the plates is measured aiming at providing evidence of the numerical model.Based on the physical tests, multiple influencing parameters around a wide range of scale are tested, and the effect of different influencing parameters on wave forces is studied. Through analyzing wave particle velocity pattern and the distribution of wave pressure, the wave-dissipating mechanism and force mechanism are studied. The main research results are listed as following:1. Relative plate width(B/L) and the relative water depth(d/L) are the most important parameter that influences the wave-dissipating performance of the shallow submerged horizontal twin-plate breakwater, and relative distance of two plates(S/H) has small influence on the transmission coefficient2. As for B/L, the wave-dissipating performance is better not because of the wider of plate. The transmission coefficient fluctuates with the increase of B/L (B/L=0.5～1.5). When relative submerge deep(d1/H)=0.4～1.33, S/H=1.0～1.67, B/L=0.8～0.9, the wave-dissipating performance of twin-plate breakwater is optimaL3. As for d/L, the smaller of the d/L, the better the wave-dissipating performance is. When d1/H=0.4～1.33, B/L=0.284～0.67, d/L<0.2, the transmission coefficient is smaller than0.4; when d/L=0.2-0.3, the transmission coefficient changes between0.4and0.7.4. The total of upper plate is almost the same as that of the twin-plate, and they have the similar change trend with the change of B/L, S/H, d/L. The total force of the down plate is much smaller.5. One of the wave-dissipating mechanism of the twin-plate breakwater can be regarded as the blocking-up of normal progression of the waves. The elliptic motion of wave particle is separated and turned into multilayer complex water movement form. In the water area between the two plates, return flow is the main water movement form and the water particles move horizontally. At the front of and the back of the twin-plate breakwater, strong turbulent fluctuation and vortex motion are the main water movement form. Below the breakwater, water particles also move horizontally.6. The collision between progressing waves and return flow is the main factor that generates impact pressure on the surface of the twin-plate breakwater. The front and back end of the upper surface of the upper plate are more likely to be influenced by impact pressure.更多还原