Vortical Structure of Turbulent Shear Flows Studied by Vortex Dynamics Simulation

涡动力学模拟研究湍流剪切流的涡结构

• 批准号: 01460108
• 负责人: KIYA Masaru
• 金额: $ 4.61万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01460108/
• 关键词: Turbulent Shear Flow; Vortex Dynamics; Three-Dimensional Flow; Vortex Method; Homogeneous Turbulence; Jets; Wakes; Coherent Vortical Structure; 組織構造; 渦相互作用; 組織的構造; 混合層; 乱流構造

1. Evolution of square vortex rings with rounded corners was simulated by a vortex blob method, in which the connectivity of vortex filaments is not explicitly maintained, to obtain patterns of deformation and the exetnt to which dynamical invariants of the three-dimensional inviscid vortex motion are really conserved. The simulation showed that the invariants were conserved until their catastrophic increase took place. The kinetic energy was found to serve as the most stringent criterion to discuss the conservation of the invariants. The time when the catastrophic bahavior appeared increased with increasing radius of core of the vortex blobs and with increasing radius of curvature of the corners. Evolution of topology of the vortex rings was obtained and discussed.2. A vortex dynamics simulation was made on the deformation of pseudoelliptical vortex rings which consists of two parallel line segments connected by two semicircles of the same radius, the major-to-minor axis ratio being b … More etween 2 and 20. The deformation had four fundamental patterns depending on the aspect ratio : the periodic axis switching ; the splitting into two vortex rings after the axix switching ; the splitting into two vortex rings without the axis switching ; the splitting into three vortex rings without the axis switching. The last two patterns are expected to lead to further axis switching and eventual splitting into two vortex rings at larer times. This was confirmed by a flow visualization experiment.3. An inviscid vortex dynamics simulation of interaction of several circular vortex rings produced the power spectrum which had a part of the Kolmogorov -5/3 power law. The enstrophy spectrum, which is equivalent to the dissipation spectrum in homogeneous turbulence, had a part of the 1/3 power law in the same wavenumber range. This study is among the first to show the -5/3 power spectrum as a result of the inviscid interaction of several, not many, vortex rings. The wavenumber range of the -5/3 power law slightly depends on the number of the vortex rings and their initial configuration, being wider for smaller radius of core of the vortex rings. A uniform distribution of high-vorticity regions appears to be essential to have the -5/3 power law. Five invariants of the inviscid vortical motion, i. e. The total energy, total momentum, total angular momentum, total helicity and total vorticity were maintained constant within tolerable deviations from the corresponding initial valves until vorticity tends to diverge.4. The unsteady separated flow around an inclined circular disk was simulated by the vortex blob method to obtain the evolution of three-dimensional vortical structures from circular vortex rings formed by the separation from the edge of the disk. A spiral structure of the vortical wake was confirmed by the simulation in terms of the vorticity contour in planes normal to the direction of the approaching flow. Less

1。用圆角的方形涡流环的演变通过涡旋斑点法模拟，其中未明确维护涡旋细丝的连通性，以获得变形模式以及三维Invortex Invortex涡旋运动的动态不变性的exetnt。模拟表明，不变剂是保守的，直到发生灾难性增加为止。发现动能是讨论不变式保护的最严格标准。灾难性巴哈维尔（Bahavior）出现的时间随着涡旋斑点的核心半径的增加而增加，角落曲率的半径增加。获得并讨论了涡旋环的拓扑演出2。进行了涡流动力学模拟，对伪圆涡流环的变形进行了模拟，该涡流环由两个平行线段组成，该线段由两个半径的两个半圆连接，主要轴比率为b…b…更加介于2和20之间。该变形具有四个基本的模式，取决于纵横比：周期轴切换。 Axix开关后，将其分为两个涡流环；分为两个无轴切换的涡流环；分为三个涡旋环，没有轴切换。预计最后两种模式将导致进一步的轴切换，并最终在拉勒时代将两个涡流环分为两个涡流环。通过流动可视化实验证实了这一点。3。几个圆形涡流环相互作用的无关涡流动力学模拟产生了具有Kolmogorov -5/3功率定律的一部分的功率谱。肠谱相当于均匀湍流中的耗散光谱，在相同的波数范围内具有1/3功率定律的一部分。这项研究是最早显示出-5/3功率谱的结果之一，这是由于几个（不多）涡流环的相互作用而导致的。 -5/3功率定律的波数范围略微取决于涡旋环的数量及其初始配置，对于涡旋环的核心核心半径较小。具有-5/3功率定律的高涡度区域的统一分布似乎至关重要。无粘性涡旋运动的五个不变性，即总能量，总动量，总角动量，总的螺旋性和总涡度在与相应的初始瓣膜相应的可容忍的出发范围内保持恒定，直到涡度趋于差异。4。通过涡旋斑点方法模拟了围绕倾斜圆盘的不稳定分离的流动，以从与磁盘边缘分离形成的圆形涡流环中获得三维涡流结构的演化。模拟通过涡度轮廓正常与接近流动的方向呈涡度轮廓来证实涡旋唤醒的螺旋结构。较少的

项目成果

M. Kiya and H. Ishii: "Deformation and Splitting of Pseudoelliptical Vortex Rings" Advances in Turbulence. 3. (1991)

M. Kiya 和 H. Ishii：“伪椭圆涡环的变形和分裂”湍流研究进展。

O.Mochizuki and M.Kiya: "Reduction of Sound Generated by a Plane Jet Impinging on a Circular Cylinder" Proceedings of the 10th Australasian Fluid Mechanics Conference,Melbourne,1989. 5.31-5.34 (1989)

O.Mochizuki 和 M.Kiya：“减少平面射流撞击圆柱体产生的声音”第十届澳大利亚流体力学会议论文集，墨尔本，1989 年。

木谷 勝・亀本 喬司・木田 輝彦・稲室 隆二: "離散渦法の基礎と応用" 朝倉書店, 260 (1992)

Masaru Kitani、Takashi Kamemoto、Teruhiko Kida 和 Ryuji Inamuro：“离散涡流法的基础和应用”朝仓书店，260 (1992)

M.KIYA,O.MOCHIZUKI and H.Tamura: "Integral Scales and Phase-Averaged Structure of Separated Turbulent Flow Zone at the Leading Edge of a Blunt Circular Cylinder" 日本流体力学会誌. 8(別冊). 304-311 (1989)

M.KIYA、O.MOCHIZUKI 和 H.Tamura：“钝圆柱体前缘分离湍流区的整体尺度和相位平均结构”日本流体力学学会杂志 8（分刊）。 304-311 (1989)

木谷勝、石井素: "3次元離散渦法における力学的保存量の評価" 第3回数値流体力学シンポジウム講演論文集. 221-224 (1989)

Masaru Kitani、Moto Ishii：“三维离散涡方法中动态守恒量的评估”第三届计算流体动力学研讨会论文集 221-224（1989）。