Graupel and Hail Terminal Velocities: Does a “Supercritical” Reynolds Number Apply?
Graupel and Hail Terminal Velocities: Does a “Supercritical” Reynolds Number Apply?
复制标题
DOI：
10.1175/jas-d-14-0034.1
复制
发表时间：
2014-08
影响因子：
3.1
通讯作者：
A. Heymsfield;R. Wright
中科院分区：
文献类型：
--
作者：
A. Heymsfield;R. Wright
摘要本研究结合最近的阻力系数和颗粒体积密度观测，描述了重边缘冰晶和集合体、泥浆和冰雹的末端速度。基于适用于这些颗粒发展和下降的大气温度和压力的无量纲雷诺数(Re)-最佳数(X)方法，作者建立了一个跨越广泛颗粒尺寸范围的关系式。对于许多应用，Re-X关系可以用来导出带边粒子的终端速度。早期的观测表明，在大型球形冰雹的阻力系数急剧下降和末端速度迅速增加的情况下，出现了一个“超临界”雷诺数。作者根据对略粗糙的大冰粒的观测和模型模拟，表明临界雷诺数受到抑制，光滑球形冰粒的末端速度快速增加的情况很少发生。
AbstractThis study characterizes the terminal velocities of heavily rimed ice crystals and aggregates, graupel, and hail using a combination of recent drag coefficient and particle bulk density observations. Based on a nondimensional Reynolds number (Re)–Best number (X) approach that applies to atmospheric temperatures and pressures where these particles develop and fall, the authors develop a relationship that spans a wide range of particle sizes. The Re–X relationship can be used to derive the terminal velocities of rimed particles for many applications. Earlier observations suggest that a “supercritical” Reynolds number is reached where the drag coefficient for large spherical ice—hail—drops precipitously and the terminal velocities increase rapidly. The authors draw on observations and model simulations for slightly roughened large ice particles that suggest that the critical Reynolds number is dampened and that the rapid increase in the terminal velocity of smooth spherical ice particles rarely occur...