A COMPLETE DESCRIPTION OF THE MECHANICS OF TURBULENCE IN A MOVING FLUID

S. Shcherbakov
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Abstract

The conditions and mechanisms of events in a moving fluid are analyzed, leading to the apparent disorder of unsteady flow, known as turbulence. The method of analysis is the use of different forms of equations of motion and transfer of characteristics, the selection of stable formations in the flow structure and a description of the interaction between them. The non-trivial results of previous works are used. The transfer and transformation of disturbances of a vortex distributed in the flow is analyzed, the conditions under which insulated tubes with a helical flow appear inside the shear flow. An important condition is the short duration of vortex disturbances. Equations are obtained that describe the interaction of the main shear flow and the vortex tube, the features of which lead to flow instability. The existence of two mechanisms for the development of turbulence is shown - the autogeneration of local decelerations and the instability of stretching of vortex tubes. The self-generation mechanism is the transfer of kinetic energy from the main flow to an annular vortex with the generation of a new annular vortex. This is the main mechanism that ensures the propagation of instability downstream, arises first when the Re number increases. The tensile instability leads to the splitting of the vortex tube into independent sections, the generation of many annular vortices that fill the space and drift in it. The vortex multiplication factor in each generation increases with the Re number and can reach many thousands. The role of ordered unsteady flows in the initiation of turbulence is shown.
运动流体中紊流力学的完整描述
分析了运动流体中导致非定常流动明显紊乱的条件和机制,即湍流。分析方法是利用不同形式的运动方程和特征传递,选择流动结构中的稳定地层并描述它们之间的相互作用。使用了以前工作的非平凡结果。分析了流动中涡旋扰动的传递和转化,分析了在剪切流动中出现螺旋流动的绝缘管的条件。一个重要的条件是涡旋扰动持续时间短。得到了主剪切流与旋涡管相互作用的方程,这种相互作用的特点导致了流动的不稳定性。证明了湍流发展的两种机制的存在——局部减速的自生和涡管拉伸的不稳定性。自生机制是动能从主流向环形涡转移,同时产生新的环形涡。这是确保不稳定性向下游传播的主要机制,当Re数增加时首先出现。拉伸不稳定导致涡旋管分裂成独立的部分,产生许多环形涡填充空间并在其中漂移。每一代的涡旋倍增因子随雷诺数的增加而增加,可达数千。揭示了有序非定常流在湍流起始中的作用。
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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