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.本文用涡滴法模拟了带圆角的方涡环的演化过程，其中涡丝的连通性没有被显式地保持，以获得三维无粘涡运动的动力学不变量真正守恒的变形模式和外显式。模拟表明，不变量是保守的，直到它们的灾难性增加发生。动能被认为是讨论不变量守恒性的最严格判据。随着涡核半径的增大和角部曲率半径的增大，灾难性的扰动出现的时间也相应增加。得到了涡环的拓扑结构演化规律，并进行了讨论.对由两条平行线段和两个半径相同的圆弧连接而成的长短轴比为B的拟椭圆涡环的变形进行了涡动力学模拟 ...更多信息 在2和20之间。变形有四个基本模式取决于纵横比：周期性的轴切换;分裂成两个涡环后的轴切换;分裂成两个涡环没有轴切换;分裂成三个涡环没有轴切换。最后两种模式预计将导致进一步的轴切换，并最终分裂成两个涡环在较长的时间。流动显示实验证实了这一点.对多个圆形涡环相互作用的无粘涡动力学模拟产生了具有部分柯尔莫哥洛夫-5/3幂律的功率谱。涡度拟能谱与均匀湍流的耗散谱是等价的，在相同波数范围内，涡度拟能谱具有部分1/3幂律。这项研究是第一个显示-5/3功率谱的结果，几个，而不是很多，涡环的无粘相互作用。-5/3幂律的波数范围与涡环的数目及其初始形状有关，涡环核半径越小，波数范围越宽。高涡度区的均匀分布似乎对满足-5/3幂律是必不可少的。无粘涡运动的五个不变量，即。e.总能量、总动量、总角动量、总螺旋度和总涡量在允许的偏差内保持恒定，直到涡量趋于发散.采用涡滴法模拟了倾斜圆盘周围的非定常分离流动，获得了圆盘边缘分离形成的圆形涡环的三维涡结构演化。涡尾流的螺旋结构被证实的模拟在垂直于来流方向的平面内的涡量轮廓。少

项目成果

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。

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。

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)

石井 素・木谷 勝: "非円形渦輪の変形と分裂の数値解析" 日本機械学会編文集. (1991)

Moto Ishii 和 Masaru Kitani：“非圆形涡环变形和分裂的数值分析”，日本机械工程师学会编辑版（1991 年）。