黏性流中的链环涡管演化与螺旋度分析  

Evolution and helicity analysis of linked vortex tubes in viscous flows

作　　者：熊诗颖 杨越[1,2,3] XIONG ShiYing;YANG Yue(State Key Laboratory for Turbulence and Complex Systems,College of Engineering,Peking University,Beijing 100871,China;Center for Applied Physics and Technology,Peking University,Beijing 100871,China;Beijing Innovation Center for Engineering Science and Advanced Technology,Peking University,Beijing 100871,China)

机构地区：[1]北京大学工学院湍流与复杂系统国家重点实验室,北京100871 [2]北京大学应用物理与技术研究中心,北京100871 [3]北京大学工程科学与新兴技术高精尖创新中心,北京100871

出　　处：《中国科学：物理学、力学、天文学》2020年第4期23-31,共9页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:11522215,91541204,91841302)资助项目。

摘　　要：本文通过直接数值模拟研究了链环涡管在不可压缩黏性流中的演化过程.在初始时刻的链环涡管由两个变形的涡环组合而成,其螺旋度为依赖于涡轴参数方程的解析表达式,进而可利用该初始流场进行涡管演化研究与螺旋度分析.发现当初始链环涡管的涡量方向具有相同手性时,链环涡管和环面纽结涡管的演化具有类似的涡动力学过程;而当它们具有相反手性时,涡管间的强涡量梯度会使两涡环在短时间内产生剧烈的涡重联,从而导致涡环由快速的尺度级串过程达到类湍流状态.We report the evolution of linked vortex tubes in incompressible viscous flow using the direct numerical simulation. The initial linked vortex tube consists of two deformed vortex rings. The helicity of the constructed vortex tube satisfies an analytical expression depending on the parametric equation of central vortex axis. Thus the linked vortex tubes can be used for further helicity analysis. We find that if vorticity of the two vortex rings has the same chirality, the evolution of linked and knotted torus vortex tubes has similar vortex dynamics. In contrast, for the opposite initial chirality, the vortex rings can have intensive reconnection after a short time due to the large vorticity gradient between the rings, resulting in rapid scale cascade towards a turbulent-like flow state.

关 键 词：涡管 螺旋度分析 涡动力学 

分 类 号：O357[理学—流体力学]