A Wall Effects and Means of Controlling the Evolution of Swirling Flows with Vortex Breakdown

IF 1.1 4区工程技术 Q4 MECHANICS

Journal of Applied Fluid Mechanics Pub Date : 2023-11-01 DOI:10.47176/jafm.16.11.1767

A. Meziane, M. Hachemi, M. Kessal, M. Imoula

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引用次数: 0

Abstract

This paper investigates numerically the bubble-type vortex breakdown apparition in the case of closed rotating flows of a viscous, axisymmetric, and incompressible fluid. First, a truncated conical/cylindrical cavity of spherical end disks is used to simulate and analyze the vortex structure under rigid surface conditions. The geometric effects of the enclosure are also studied. Vortex breakdown is demonstrated beyond the lower disk rotation rate threshold by introducing the no-slip condition imposed on the upper wall. The objective is to explore ways of controlling the evolution of this physical event by modifying the confinement conditions upstream of the vortex rupture. Particular attention is also paid to the effective kinematic viscosity, thermal diffusivity and geometric control of recirculation zones on the axis of rotation (axial bubble type). The second geometry consists of a spherical annulus formed by two concentric hemispheres in differential rotation under plat-free surface conditions. The results show that rotation of the inner hemisphere induces a vortex bubble on the polar axis. In contrast, the outer hemisphere rotation induces a toroidal vortex on the equator.

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A壁效应及控制旋涡破裂旋流发展的方法

本文数值研究了粘性、轴对称和不可压缩流体在闭合旋转流情况下的气泡型旋涡破裂现象。首先，利用球形端盘的截锥/圆柱形空腔对刚性表面条件下的涡流结构进行了模拟和分析。还研究了围护结构的几何效应。通过引入施加在上壁上的无滑移条件，证明了涡流击穿超过了较低的圆盘转速阈值。目的是通过改变涡旋破裂上游的约束条件，探索控制这一物理事件演变的方法。还特别注意旋转轴上再循环区（轴向气泡型）的有效运动粘度、热扩散率和几何控制。第二种几何形状由两个同心半球在无平面条件下差动旋转形成的球面环组成。结果表明，内半球的旋转会在极轴上产生旋涡气泡。相反，外半球的自转在赤道上引发了一个环形涡旋。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Applied Fluid Mechanics THERMODYNAMICS-MECHANICS

CiteScore

2.00

自引率

20.00%

发文量

138

审稿时长

>12 weeks

期刊介绍： The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating. The motivation for this new fluid mechanics journal is driven by the following points: (1) there is a need to have an e-journal accessible to all fluid mechanics researchers, (2) scientists from third- world countries need a venue that does not incur publication costs, (3) quality papers deserve rapid and fast publication through an efficient peer review process, and (4) an outlet is needed for rapid dissemination of fluid mechanics conferences held in Asian countries. Pertaining to this latter point, there presently exist some excellent conferences devoted to the promotion of fluid mechanics in the region such as the Asian Congress of Fluid Mechanics which began in 1980 and nominally takes place in one of the Asian countries every two years. We hope that the proposed journal provides and additional impetus for promoting applied fluids research and associated activities in this continent. The journal is under the umbrella of the Physics Society of Iran with the collaboration of Isfahan University of Technology (IUT) .