关于旋涡定义的思考

吴介之; 杨越

doi:10.7638/kqdlxxb-2019.0171

关于旋涡定义的思考

doi: 10.7638/kqdlxxb-2019.0171

吴介之,
杨越

北京大学工学院湍流与复杂系统国家重点实验室, 北京 100871

基金项目:

国家自然科学基金 11472016

详细信息

作者简介:
吴介之(1940-), 男, 广东肇庆人, 教授, 硕士, 主要从事复杂流动多过程分解耦合研究.E-mail:jie_zhi_wu@163.com

中图分类号: V211.3
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- 被引次数: 0
出版历程
- 收稿日期: 2019-12-13
- 修回日期: 2019-12-24
- 刊出日期: 2020-02-25

Thoughts on vortex definition

WU Jiezhi,
YANG Yue

State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China

摘要

摘要: 针对旋涡定义这个长期未解决的难题，在分析历史上提出的几种思路的基础上，本文提出：定义旋涡的总目标，应当体现其管状运动形态，并与其作为流体运动肌腱的动力学功能有机结合；该定义应能以统一的方式覆盖经典涡动力学业已成熟的结果，并且指引对湍流中复杂涡状结构及其相互作用的识别。据此，本文根据涡量场演化的已知规律，提出了旋涡的一个动力学定义，作为继续深化讨论的参考。同时提出，人们针对湍流结构研究构造的各种涡判据，虽然对湍流涡状结构的可视化起了重要作用，但因其难以遵循管式涡量场的因果演化而无法取代完备的涡定义。相比之下，近十年来形成的涡量面理论，有望在未来发展中使旋涡的定义和检验问题回归涡量动力学的自然规律。
- 旋涡 /
- 涡动力学 /
- 涡定义 /
- 涡判据 /
- 湍流结构
Abstract: Aiming at the long unsolved issue of vortex definition, this article reviewed critically those historically appeared definitions, and thereby proposes that the general goal of vortex definition should reflect an inherent combination of the solenoidal nature of vortices in kinematics and their role as the sinews and muscles of fluid motion in dynamics. The definition should, in a unified manner, cover all mature achievements of classic vortex dynamics and guide the identification of complex vortical structures and interactions in turbulence. Thus, on the basis of the known evolution laws of vorticity field, we propose a dynamic definition of vortices as a reference of further discussion. Although various "vortex criteria" constructed for visualizing turbulent structures have played important role in one's understanding, they cannot replace a complete vortex definition since they do not follow the causal evolution rules of the solenoidal vorticity field. In contrast, it is expected that the vorticity-surface theory formed in the past decade will, in its future development, be able to bring the definition of vortex and its testing back to the natural laws of vorticity dynamics.
- vortices /
- vorticity and vortex dynamics /
- vortex definition /
- vortex criteria /
- turbulent structure

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图 1 从左向右突然起动的翼型的起动涡和升力涡^[3]

Figure 1. The starting vortex and lifting vortex formed during the suddenly started motion of an airfoil from left to right. From Tietjens & Prandtl (1934)^[3]

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图 2 三维尾涡

Figure 2. Three-dimensional wake wortices

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图 3 一端有界的面涡卷绕，(Betz, 1950^[18])

Figure 3. The rolling-up of a semi-infinitely extended vortex sheet (Betz, 1950^[18])

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图 4 受扰无限长面涡因Kelvin-Helmholtz不稳定性和自诱导而发展成卷绕涡列(Krasny, 1988^[19])

Figure 4. The evolution of disturbed infinitely extended vortex sheet into rolled-up vortex array due to Kelvin-Helmholtz instability and self-induction (Krasny, 1988^[19])

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图 5 积雨云和龙卷风^[20]

Figure 5. Cumulonimbus and tornado^[20]

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图 7 Moore-Saffman尾涡模型的周向与轴向速度分布

Figure 7. Profiles of circumferential and axial velocities of Moore-Saffman trailing vortex model

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图 6 Moore-Saffman尾涡模型的核结构

Figure 6. Core structure of Moore-Saffman trailing vortex model

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图 8 用一族涡量面算出的发卡涡列的形成与演化^[28]

Figure 8. The formation and evolution of a series of hairpin vortices, computed by a set of vorticity surfaces^[28]

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