流体微团运动变形特性分析

Analysis on element deformation

流体微团的变形与运动互为因果。由于流体的易流动性,流体微团变形比固体复杂、多样。认识流体变形特性是分析流体宏观运动的基础,在流体力学及其工程应用中占有重要地位。在过去的研究中,由于一般都孤立地讨论流体微团的各种变形,结果难以发现这些变形之间的联系,同时也丧失了一些发现流体微团特定运动规律的机会。为弥补过去研究的不足,本文在分析流体微团各种可能变形的联系的基础上,以矢量分析为工具,导出了在特定条件下各种变形的特点。本文的主要成果在于获得了过去文献中没有提到过的流体微团运动、变形的两项特征:当流体微团在无变形条件下仅有旋转运动时,微团将像刚体一样绕基点作定轴转动;当流体微团仅有剪切变形时,两直角边将相向等速运动,正方形微团变形为一菱形。

Motion of a fluid element is induced by its motion, verse visa. Fluid deformation is more complicated and diversibied than that of a solid body. Fluid deformation is the foundation of macro fluid motion analysis and is of prime importance on fluid mechanics and its applications in all branches of industry. In past research, however, experts focused their study on separate analysis of deformation, making it impossible to find out the relationship of these deformations and some special laws of each deformation. Based on analyzing the relationship of fluid deformation and vectoral computation, authors of this paper derived some characteristics of fluid deformation which were not shown in previous literatures. The most important results presented in this paper include two aspects of fluid element motion： when the element purely rotates about one special point without deformation, the element will rotate like a solid body with even angular speed, and when only shear deformation occurs, two sides of a right angle will move in opposite directions with equal speed, making a rectangular element become a diamond.