【作者】 姜昭阳；

【导师】 梁振林；

【作者基本信息】 中国海洋大学 ， 增殖养殖工程， 2009， 博士

【摘要】 人工鱼礁是指由一个或多个自然或人造物体组成,并有目的的设置于海底,用来改变海洋生物资源与环境,进而促进社会经济发展的人工设施,是海洋牧场工程建设的重要组成部分。与其他海洋结构物一样,人工鱼礁在海底受到水流等水文环境因素的作用,其流场效应和受力状况与其自身的水动力学性能密切相关。关于人工鱼礁水动力学性能的研究,人们在以往的研究中通常借助于传统的渔具力学理论和动力水槽实验等方法来进行研究,而这些方法往往会受到理论深度、流体属性、观测方法和精度、人力和物力等诸多方面的影响或限制,无法满足人们对人工鱼礁水动力学性能全面认识的需求。本论文以不同人工鱼礁模型为研究对象,依据计算流体力学理论为基础,基于大型计算流体力学软件Fluent为平台,运用三维湍流模拟技术为研究手段,开展了人工鱼礁模型水动力学性能的数值模拟研究,得到了人工鱼礁模型各断面压力分布、流场效应和礁体的受力情况,揭示了人工鱼礁局部流场的流动结构;同时与动力水槽实验,特别是粒子图像测速(PIV)技术的实测结果进行对比分析,结果均比较吻合,使得两类方法得到了相互验证,并对各礁体模型所产生的流场效应作初步比较。由此说明,本论文所采用的数值模拟方法可以对人工鱼礁水动力学性能的预测,进而推广到实际的人工鱼礁水动力学性能研究中去,旨在为人工鱼礁流场理论的初步研究和设计的选型优化奠定理论基础,为我国日益蓬勃发展的人工鱼礁区规划和建设事业的全面发展提供科学参考。首先,本论文建立了一套针对多孔立方体人工鱼礁模型的三维湍流流动数值模拟模型,对其水动力学性能进行了数值模拟,预测了模型礁体周围及其内部三维流动结构和基本流态,分析了压力和流速分布之间的关系,得到了人工鱼礁模型的受力值和流速值。计算结果与动力水槽实验数据进行比较,均比较吻合,受力和速度的计算值与测量值之间的相对误差都很小,分别在2.3 %～26.2 %和1.3 %～36.4 %之间。这说明,两种方法均能体现模型礁体在流速增加时,受力增加的趋势,且数值模拟结果基本符合模型礁体局部绕流流场的特征。其次,以单孔立方体人工鱼礁模型为研究对象,在应用三维湍流流动模型进行非定常流动数值模拟的同时,利用PIV技术对横流中人工鱼礁绕流流场纵向断面处各局部的流动特性进行测量,清晰地了解到模型礁体的上升流区、尾流区、迎流区和内部旋涡的交替产生、发展和消亡的过程,并对主要旋涡运动的周期和影响范围做出了相应的分析。数值模拟结果与PIV实测和测力实验结果进行对比,结果较吻合,符合人工鱼礁模型局部流场的流动结构,及模型的受力情况。再次,运用三维湍流数值模拟技术,对梯形台人工鱼礁模型在横流作用下的非定常流动进行了数值模拟,了解了梯形台模型礁体的流场效应,通过与PIV实测流场以及测力实验的结果进行比较,数值模拟结果与实验测量结果吻合较好,进一步表明本文的数值计算和性能预测均能达到一定的精度。并对三种礁体的上升流及影响范围等进行了比较。最后,依据计算流体力学理论,运用三维湍流模拟技术,对人工鱼礁板块区内的流动进行数值模拟,得到了人工鱼礁区生态系统中单位板块区的流场分布情况,能够让人们直观地了解到人工鱼礁板块区所产生的流场效应,为研究人员提供人工鱼礁区规划和建设的科学参考。更多还原

【Abstract】 An artificial reef is one or more objects of natural or human origin deployed purposefully on the seafloor to influence physical, biological, or socioeconomic processes related to living marine resources, and it is the important component of the construction of marine ranching engineering. Just like other ocean engineering structures, artificial reefs on sea bottom are withstood by the hydrological environment effects responded by the current conditions, and then the perspective of flow field effect and forces stood are nearly correlated with theirs hydrodynamic capability under the ocean field conditions. About the studies of the hydrodynamic capability of artificial reef, researchers usually recur to the reference of traditional fishing gear hydrodynamics and flume tank experiments. However, these methods may be affected or limited by theoretical profundity, fluid attributes, meterage methods and precision, manpower and material resources, etc, which can’t meet the requirement of complete understanding for the hydrodynamics of artificial reef.This paper, aimed at artificial reef model, according as computational fluid dynamics, based on the Fluent CFD code, utilized three-dimensional turbulent model to simulate the hydrodynamic capability of artificial reef models. The pressure distribution, flow field effect and forces stood of model reefs are obtained, which shows the flow field structure on the locals of artificial reefs. A good agreement is achieved between numerical results with flume tank experiments data, especially, the particle imagine velocimetry data. It suggested that the numerical simulation method adopted in this paper can be applied to predict the hydrodynamic capability of artificial reefs, and then popularize this method in the study of actual artificial reef. Its achievement will establish the theoretical foundation for the pilot study of artificial reef flow field theory and designs optimized, and supply the scientific reference to the progressive development of layout and construction of artificial reef areas.Firstly, a numerical simulation model of RNG k -εturbulent flow aimed at apertured cube artificial reef model is established in this paper. By use of this numerical model, the three-dimensional flow structure is predicted; the relationship between pressure and velocity is analyzed; and the values of forces stood and velocities are obtained. Numerical results have a good coherence compared with experiments data; the relative errors between the numerical and metrical are all small, which are in range of 2.3 %~26.2 % and 1.3 %~36.4 % respectively. It suggested that both the numerical and experimental methods could represent the increase trends of forces stood with the flow velocities increasing, and numerical results are basically accorded with the flow field characteristic of cross flow past the locals of model reef.Secondly, aimed at a single apertured cube artificial reef model, three-dimensional turbulent model is applied to simulate the unsteady flow of cross flow; simultaneous, by the PIV technology, the flow characteristic on the longitudinal central section of flow field of cross flow pasting the artificial reef model is measured, and the dynamic process of the vortex alternative formation, its development and extinction are realize clearly, where are in the upstream, the wake, the front, the inside areas respectively. Numerical results have a good coherence compared with PIV data, which agrees with the flow structure on the locals of artificial reef model and the forces stood by model.Thirdly, by three-dimensional numerical simulation technology, the unsteady flow of cross flow past a trapezoid platform artificial reef model is simulated, and the flow field effect of trapezoid platform reef model is realized. Numerical results have a good coherence compared with PIV data. These results can more indicate that both the numerical computation and characteristic predictions in this paper achieve a precision to some extent. And the incidence of upwelling and flow field were compare within three kind of artificial reef model.Finally, based on computational fluid dynamics theory, three-dimensional turbulent model is adopted to simulate the flow in artificial reef block, and flow field distribution in block of artificial reef ecosystem. It is feasible for people to realize the flow field effect of artificial reef block intuitively, and then supply scientific reference to the layout and construction of artificial reef areas.更多还原