摘 要

圆柱绕流作为最常见的钝体绕流现象，一直作为众多研究学者的理论分析和实验研究的热点。

流场中固体的外形和位置对流场的流速、迹线的分布有着重要的影响。流场中流体绕流固体时，由于流体流经固体表面时迹线会产生分离，在固体的背面由于负压而形成漩涡，使得结构在流场中收到不均匀的周期性的载荷，该载荷可能导致结构发生周期性振动，如载荷频率达到与固体结构固有频率相同或相近时而引起共振，将导致灾难性的事故和后果。如河流中的桥梁、海洋中的工作平台、隧道中行驶的汽车等情况。因此，研究流场中的绕流问题，分析流场中固体对流场流速分布的影响以及涡流现象对固体作用的响应，为分析和解决工程中的绕流问题提供理论基础，该工作具有重要的科学研究意义和工程应用价值。

本文采用CFD方法，对二维流场的单圆柱绕流及并列双圆柱绕流进行了数值模拟。以往的具体实验研究方法受制于资金、试验周期、实验设备大小等问题，存在很多的局限性，得到的结果也被后来的研究证明缺乏较高的精确性。通过对文献资料的研究，发现采用数值模拟的方法，对于圆柱绕流进行模拟，会得到比较理想的结果，有较高的还原度。本文所采取的研究方法，能够避免实验设备、实验模型、经费等的限制，具有较好的仿真度，以及有比传统实验方法更好的可调整性及适用性。又因为其应用面更广，能模拟更多的圆柱绕流情况，所以在各研究领域均得到了广泛的应用。

本文采用ANSYS通用软件包中的计算流体力学分析软件FLUENT，结合不可压缩流体的纳维-斯托克斯方程，对固定单圆柱、并列双圆柱两种模型的圆柱绕流流场做了二维的数值仿真分析，通过在求解器中不同的参数设置，得到了单、双圆柱周围流场的流型，涡量等值线和速度矢量图等，得到不同流速和圆柱尺寸对流场分布的影响，并通过数值模拟的结果分析了圆柱的受力情况以及圆柱尾部涡流的运动和脱落情况。

本文的研究成果有助于理解流场初始流速以及圆柱尺寸对圆柱绕流问题中的流场分布的影响，以及圆柱的复杂受力情况，这些成果对于理论研究领域和工程应用领域中的钝体绕流相关问题具有一定的实际意义。

关键词：圆柱绕流；FLUENT；数值模拟；尾涡脱落

Abstract

As one of the most common flow phenomena around a bluff body, the flow around a cylinder has been the focus of theoretical analysis and experimental research of a large number of research scholars.

Shape and position of the flow rate of the flow field flow field of solids, traces the distribution has a significant impact. When the flow field of fluid flow around a solid, since the fluid flows through the solid surface will produce traces separated solid at the back because of the negative pressure and swirl so uneven structure receive periodic load in the flow field, the loads may cause structural vibrations occur periodically, such as the frequency of the load with the same or similar solid structure natural frequency resonance sometimes will lead to accidents and catastrophic consequences. As the river bridge, ocean work platform, tunnel driving cars and so on. Therefore, the study of the flow field flow around, flow field analysis of the response of the solid flow field velocity distribution as well as the impact of the phenomenon of vortex solid role, provide a theoretical basis for analyzing and solving engineering flow around the work of an important scientific research and engineering application value.

In this paper, the CFD method is used to simulate the flow around a single cylinder and two parallel cylinders. In the past, the specific experimental methods are subject to the funding, test cycle, the size of the experimental equipment and other issues, there are many limitations, the results obtained by the subsequent studies have shown a lack of high accuracy. Through the research of literature data, it is found that the numerical simulation method is used to simulate the flow around a circular cylinder, which can get the ideal result, and has a high degree of reduction. The research methods adopted in this paper can avoid the limitation of experimental equipment, experimental model, funds and so on. It has a good simulation degree, and can be adjusted and applied better than the traditional method. Because of its wider application, it can simulate the flow around the cylinder, so it has been widely used in various research fields.

The ANSYS general purpose software package in the computational fluid dynamics analysis software FLUENT, combined with the incompressible Navier-Stokes equations, of fixed single cylinder, parallel double cylinder model of cylindrical flow around two-dimensional numerical simulation analysis by different in the solver parameters settings, single, double cylindrical flow field around the pattern.Different velocity and cylinder size influence on flow field distribution, and the numerical simulation results analysis the cylinder force and cylindrical tail vortex flow movement and shedding.

Results of this study help to understand the initial flow velocity and cylinder size of cylindrical winding flow problem in the distribution of flow field, and the cylindrical complex stress condition. These achievements in the fields of theoretical research and engineering application of flow around a bluff body related issues has a certain practical significance.

Key words: Flow around cylinder; FLUENT; Numerical simulation; Vortex shedding

目 录

第1章 绪论 1

1.1 研究背景及意义 1

1.2 圆柱绕流机理与相关概念 2

1.2.1边界层理论概述 2

1.2.2 圆柱绕流的卡门涡街 3

1.3 关于圆柱绕流现象的国内外研究进展 4

1.4 本文的工作内容 4

第2章 FLUENT软件基本理论 6

2.1 FLUENT软件介绍 6

2.1.1 FLUENT单元介绍 6

2.1.1 求解步骤 6

2.1.3 湍流控制方程 7

第3章 圆柱绕流二维数值模拟结果及分析 9

3.1 单圆柱绕流数值模拟 9

3.1.1 单圆柱绕流流场的计算域 9

3.1.2 单圆柱绕流模型网格划分 9

3.1.3 单圆柱绕流边界条件 9

3.1.4 单圆柱绕流求解器设置 10

3.1.5 单圆柱绕流数值模拟结果 10

3.2 并列双圆柱绕流数值模拟 17

3.2.1并列双圆柱绕流流场的计算域 17

3.2.2 并列双圆柱绕流模型网格划分 17

3.2.3 并列双圆柱数值模拟结果 18

3.3 本章小结 22

第4章 结论与展望..........................................................23

4.1 结论 23

4.2 展望 23

参考文献 24

致谢 25

第1章 绪论

1.1 研究背景及意义

流场中固体的外形和位置对流场的流速、迹线的分布有着重要的影响。流场中流体绕流固体时，由于流体流经固体表面时迹线会产生分离，在固体的背面由于负压而形成漩涡，使得结构在流场中收到不均匀的周期性的载荷，该载荷可能导致结构发生周期性振动，如载荷频率达到与固体结构固有频率相同或相近时而引起共振，将导致灾难性的事故和后果。如河流中的桥梁、海洋中的工作平台、隧道中行驶的汽车等情况^[1-2],如图1.1所示。因此，研究流场中的绕流问题，分析流场中固体对流场流速分布的影响以及涡流现象对固体作用的响应，为分析和解决工程中的绕流问题提供理论基础，该工作具有重要的科学研究意义和工程应用价值。