基于SPH方法波浪与开孔沉箱式防波堤相互作用的数值研究

发布时间：2018-05-03 04:31

本文选题：开孔沉箱 + 波浪力　；参考：《大连理工大学》2016年博士论文

【摘要】：进入21世纪以来,海洋资源的开发得到了越来越多的重视,海洋灾害的预防和治理工作刻不容缓,掌握波浪与海洋工程结构物相互作用机理就显得格外重要。由于这类水动力学问题的复杂性,以往模型实验和理论方法的研究,不仅耗时、成本高,而且在实体复杂结构模拟、问题域简化假设等诸多因素影响下,很多细节问题和物理现象不能得到深入的研究。因此,亟需一种计算机高级仿真技术来解决这一复杂科研课题。SPH(光滑粒子流体动力学)算法的提出可以弥补这一领域数值研究方法的空缺,其无网格和自适应特性,使得SPH方法明显优于以往基于网格的有限元(FEM)和离散元(DEM)等数值方法。因此,将SPH近似算法应用到水动力学问题研究中将成为当前这一学科的热点。在深入研究SPH方法的基础上,本文首先将水动力问题域进行离散化处理；采用SPH近似算法对Navier-Stokes水动力学控制方程组进行了逼近求解,得到了适用于研究波浪与结构物相互作用问题的水动力数学模型；采用虚粒子对沉箱模型进行了数值模拟,满足了沉箱边界的不可穿透性；基于CSPM和Riemann解相结合的方法对SPH方法进行了修正,成功地建立了模拟波浪与开孔沉箱相互作用的二维数值波浪水槽；对沉箱固壁边界粒子受到的波压力进行了修正,实现了流体与沉箱边界压力的稳定传递；通过多个数值算例将SPH计算结果与线性规则波理论值对比,验证了SPH近似算法的正确性。本文通过对波浪与无顶板开孔沉箱实验过程的数值模拟,研究了无顶板开孔沉箱反射系数Kr1、总水平力与消浪室相对宽度B/L、相对波高H/L等影响因素之间的关系,得出与物理模型实验拟合关系式相一致的结论,精细地研究了开孔沉箱消浪室内外波压力的分布规律,为无顶板开孔沉箱的工程设计提供了新的参考依据；本文还研究了规则波作用下无顶板开孔沉箱消浪室内外水粒子压力场、速度场变化特性,对水粒子出入消浪室复杂的物理过程进行了分析,详细讨论了消浪室内部速度场的变化情况。其次,基于改进后SPH数学模型,考虑到顶板高差对有顶板开孔沉箱水动力性能的影响,对波浪与有顶板开孔沉箱实验过程进行了数值模拟,对顶板相对高差s/H与反射系数之间的关系进行了研究,得出了有顶板开孔沉箱反射系数与其影响因素s/H是非线性关系的结论,并通过实验结果验证了此结论的正确性。文中分析了顶板高差对波面及波压力的影响,给出了波压力沿有顶板开孔沉箱高度方向的分布规律。同时,本文研究了顶板相对高差与总水平力的非线性关系,并将其与实验拟合关系式进行了对比,得出了一致的结论,文中还研究了顶板高差对总水平力与开孔板前后、消浪室后墙所受到的水平力组分的影响,对不同顶板高差时消浪室内外压力场、速度场进行了分析,并对有顶板开孔沉箱消浪室内水粒子速度场变化情况进行了细致地讨论。最后,将SPH方法与有限元计算程序对接,展开对开孔沉箱水动力作用下瞬态动力响应问题的研究。文中通过对液仓-弹性板相互作用实验过程的数值模拟,验证了瞬态动力分析方法的正确性。本文研究了波浪荷载作用下沉箱动应力变化情况,给出了有顶板开孔沉箱动应力分布规律,分析了不同顶板相对高差s/L和不同消浪室相对宽度B/L对开孔沉箱应力的影响,并得出了开孔板动应力自开孔板中心向两侧先减小后增大非线性变化的重要结论,通过SPH方法与有限元程序的对接为波浪作用下开孔沉箱结构动力响应问题研究提供了一个新的技术手段。
[Abstract]:Since the twenty-first Century, more and more attention has been paid to the development of marine resources. The prevention and control of marine disasters is of great urgency. It is very important to master the interaction mechanism of waves and marine engineering structures. The cost is high, and many details and physical phenomena can not be deeply studied under the influence of the complex structure simulation of the entity and the simplified hypothesis of the problem domain. Therefore, a computer advanced simulation technology is urgently needed to solve this complex research topic.SPH (smooth particle fluid dynamics) algorithm can make up for this The vacancy of the domain numerical research method, its meshless and adaptive characteristics makes the SPH method obviously better than the numerical methods such as FEM and DEM based on grid. Therefore, the application of the SPH approximation algorithm to the study of the hydrodynamic problems will become a hot topic in this subject. On the basis of the in-depth study of the SPH method, this paper is based on the study of the SPH method. First, the hydrodynamic problem domain is discretized, and the SPH approximation algorithm is used to approximate the Navier-Stokes hydrodynamics control equations. The hydrodynamic mathematical model is obtained for the study of the interaction between wave and structure, and the caisson model is numerically simulated with the virtual particle, which satisfies the caisson boundary. The SPH method is modified based on the combination of CSPM and Riemann solution. The two-dimensional numerical wave flume is successfully established to simulate the interaction between the wave and the open caisson. The wave pressure on the particle boundary particles in the solid wall of the caisson is corrected, and the steady transfer of the boundary pressure between the flow body and the caisson is realized. By comparing the SPH calculation results with the linear regular wave theory, the correctness of the SPH approximation algorithm is verified by several numerical examples. Through the numerical simulation of the experimental process of the open caisson in wave and roof free open hole, the influence factors such as the reflection coefficient Kr1 of the open caisson without roof open hole, the total horizontal force and the relative width B/L of the wave eliminating chamber and the relative wave height H/L are studied. The relationship between them is consistent with the fitting formula of the physical model experiment. The distribution law of the external wave pressure in the open caisson wave elimination chamber is carefully studied, which provides a new reference for the engineering design of the open caisson without roof. In this paper, the pressure of the external water particle pressure in the open caisson without roof Open Caisson under the action of the regular wave is also studied. The force field and the velocity field change characteristics are analyzed and the complex physical process of the water particle entry and exit chamber is analyzed. The change of the velocity field in the wave elimination chamber is discussed in detail. Secondly, based on the improved SPH mathematical model, considering the effect of the roof height difference on the hydrodynamic energy of the open caisson with a top plate, the experiment on the wave and the open caisson with a roof with a roof has been tested. The relationship between the relative height difference s/H of the roof and the reflection coefficient is studied. The conclusion is drawn that the reflection coefficient of the caisson with the top plate and its influence factor s/H is nonlinear, and the correctness of the conclusion is verified by the experimental results. The distribution law of the wave pressure along the height direction of the caisson with a roof opening is presented. At the same time, this paper studies the nonlinear relation between the relative height difference of the roof and the total horizontal force, and compares it with the experimental fitting relation, and draws a consistent conclusion. The paper also studies the height difference of the roof to the total horizontal force and the opening plate, the rear wall of the wave eliminating chamber. The influence of the horizontal force component is analyzed on the pressure field and the velocity field of the wave dissipating room at different roof height differences, and the velocity field of the water particle in the caisson chamber with a roof open caisson is discussed carefully. Finally, the SPH method is butted with the finite element calculation program to expand the transient state of the Open Caisson under the hydrodynamic force. In this paper, the correctness of the transient dynamic analysis method is verified by numerical simulation of the experimental process of the interaction of the liquid silo elastic plate. The dynamic stress variation of the Caisson under the action of wave load is studied. The dynamic stress distribution law of the caisson with a roof open hole is given, and the relative height difference s/L of the different roof is analyzed. And the influence of the relative width of B/L on the stress of open caisson, and the conclusion that the dynamic stress of the open hole plate is reduced first to both sides and then the nonlinear change is increased. The connection between the SPH method and the finite element program provides a new technique for the study of the dynamic response of the open caisson structure under the action of the wave action. Means.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：U656.2

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