Observation of the Falling Motion of Early Snow Flakes: Part I. Relationship between the Free-fall Pattern and the Number and Shape of Component Snow Crystals@@@第1部:自由落下パターンと構成雪結晶の数および形との関係
Observation of the Falling Motion of Early Snow Flakes: Part I. Relationship between the Free-fall Pattern and the Number and Shape of Component Snow Crystals@@@第1部:自由落下パターンと構成雪結晶の数および形との関係
复制标题
早期雪花落下运动的观察：第一部分：自由落体模式与雪晶数量和形状之间的关系@@@第一部分：自由落体模式与雪晶数量和形状之间的关系水晶
DOI：
--
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
M. Kajikawa
中科院分区：
文献类型：
--
作者：
M. Kajikawa
采用立体摄影测量方法观察了由 2 至 6 个晶体组成的早期雪花的自由落体模式。相当一部分（约80%）的分析雪花呈现螺旋型或旋转型的降落模式。另一方面，仅在由两个晶体组成的少量雪花中观察到稳定运动（没有水平运动的下落模式）。这些雪花是否表现出稳定的运动取决于平均垂直运动的雷诺数、组合状态以及两组分晶体的尺寸比。螺旋运动的无量纲频率和周期分别与螺旋路径的雷诺数和无量纲振幅成正比增加。此外，螺旋轴的位移速度与早期雪花的下落速度成比例地增加。
Free-fall pattern of early snow flakes,which were composed of two to six crystals, were observed by a stereophotogrammetric method. The considerable part (about 80%) of analysed snow flakes showed the fall pattern of spiral type or rotation type. On the other hand, the stable motion (the fall pattern without horizontal movements) was only observed in the small number of snow flakes composed of two crystals. Whether those snow flakes show the stable motion or not depend on Reynolds number of mean vertical motion, the combined state and the ratio of sizes of two component crystals. The nondimensional frequency and the period of spiral motion increased in proportion to Reynolds number and the nondimensional amplitude of spiral path, respectively. Moreover, the displacement velocity of spiral axis increased proportionally to the falling velocity of early snow flakes.