The Bubble Concept of Axisymmetric Vortex Breakdown with and Without Obstacles in the Vortex Core

The Bubble Concept of Axisymmetric Vortex Breakdown with and Without Obstacles in the Vortex Core
Author: Hans J. Lugt
Publisher:
Total Pages: 35
Release: 1988
Genre:
ISBN:

There is now sufficient evidence that axisymmetric recirculation zones in the form of 'bubbles' on the axis of rotation of a vortex can be steady-state and stable. It appears also that the majority of researchers accept these bubbles as a form or a part of vortex breakdown. However, a gray area with regard to the definition of vortex breakdown exists when no stagnation point at the axis of rotation occurs. To use the appearance of such a stagnation point as a criterion for vortex breakdown might be too restrictive. The situation becomes even more aggravated when an obstacle is placed on the axis of rotation. Are recirculation (or separation) regions in the front and rear of the obstacle indications of vortex breakdown or of Taylor-Proudman columns? This report addresses some of the problems in context with vortex control. Keyword: Vortex control. (edc).

Liutex and Its Applications in Turbulence Research

Liutex and Its Applications in Turbulence Research
Author: Chaoqun Liu
Publisher: Academic Press
Total Pages: 458
Release: 2020-10-29
Genre: Science
ISBN: 0128190248

Liutex and Its Applications in Turbulence Research reviews the history of vortex definition, provides an accurate mathematical definition of vortices, and explains their applications in flow transition, turbulent flow, flow control, and turbulent flow experiments. The book explains the term "Rortex" as a mathematically defined rigid rotation of fluids or vortex, which could help solve many longstanding problems in turbulence research. The accurate mathematical definition of the vortex is important in a range of industrial contexts, including aerospace, turbine machinery, combustion, and electronic cooling systems, so there are many areas of research that can benefit from the innovations described here. This book provides a thorough survey of the latest research in generalized and flow-thermal, unified, law-of-the-wall for wall-bounded turbulence. Important theory and methodologies used for developing these laws are described in detail, including: the classification of the conventional turbulent boundary layer concept based on proper velocity scaling; the methodology for identification of the scales of velocity, temperature, and length needed to establish the law; and the discovery, proof, and strict validations of the laws, with both Reynolds and Prandtl number independency properties using DNS data. The establishment of these statistical laws is important to modern fluid mechanics and heat transfer research, and greatly expands our understanding of wall-bounded turbulence. Provides an accurate mathematical definition of vortices Provides a thorough survey of the latest research in generalized and flow-thermal, unified, law-of-the-wall for wall-bounded turbulence Explains the term “Rortex as a mathematically defined rigid rotation of fluids or vortex Covers the statistical laws important to modern fluid mechanics and heat transfer research, and greatly expands our understanding of wall-bounded turbulence