1、沙尘暴垂直输运的两相流理论：气柱挟卷模式刘飞 1、2 巢纪平 31. 中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京，1000292. 中国科学院研究生院，北京，1000493. 国家海洋环境预报中心,北京,100081摘要为了改进气块法对沙尘沉降问题的研究，文中利用气柱法，考虑沙尘气体与环境的交换作用以及气柱内湍流交换作用。计算结果表明，均匀场中有利于沉降的条件为较大的初始沙尘浓度扰动与较小的初始温度扰动，而且温度扩散系数越大越有利于沙尘沉降，沙尘浓度扩散系数越大越不利于沙尘沉降，湍流过程在均匀场中对沙尘沉降影响不大。考虑到更真实的环境场，得出在环境的垂直沙尘浓度梯度与温度梯度的
2、参数域中，初始沙尘扰动越大越有利于沙尘沉降，初始温度扰动越大，越不利于沙尘沉降。同时给出 4种不利于沙尘沉降的过程：(1）上升浓度变化过程；(2）下沉浓度变化过程；(3）上升温度变化过程；(4）下沉温度变化过程。根据这些过程分析参数对沙尘沉降的影响得到：温度扩散系数越大越有利沙尘沉降；沙尘浓度扩散系数越大不利于沙尘沉降；垂直温度湍流交换系数越大有利于缓降区甚至是非沉降区的上升；垂直沙尘浓度湍流交换系数越大越有利于沙尘沉降。关键词沙尘暴, 两相流, 沉降, 气柱挟卷模式作者简介：刘飞，主要从事大气海洋动力学研究。 E-mail:2007-09-19收稿,2007-12-27 改回.中图法分类号
3、P425.5+5P435+.1The two-phase flow theory about dust storms vertical transport, part :The air column entrainment model.LIU Fei1,2CHAO Jiping 31. Key Laboratory Regional ClimateEnvironment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China2. G
4、raduate University of Chinese Academy of Sciences, Beijing 100049, China3. National Marine Environmental Forecasting Center, Beijing 100081, ChinaAbstractTo improve the air particle method in the previous paper, the air column entrainment method is used to study dust storm sedimentation. In the meth
5、od, entrainment between the column and the environment is included, as is the turbulent exchange within the column. In a homogeneous environment, the computational results suggest that favorable conditions for sedimentation are larger initial dust concentration disturbances and smaller initial tempe
6、rature disturbances; and furthermore, the larger the diffusion coefficient of temperature, the quicker the dust sedimentation, but the larger the diffusion coefficient of dust concentration, the slower the dust sedimentation. The turbulent process has little influence on the sedimentation. We furthe
7、r consider some more real environment conditions with vertical dust concentration and temperature gradients, the results suggest the same favorable conditions for the sedimentation in the above homogeneous environment. And meanwhile, four processes which are not conducive to the sedimentation are gi
8、ven: (1) ascending concentration variation process; (2) descending concentration variation process; (3) ascending temperature variation process; (4) descending temperature variation process. On the basis of the definitions of these processes, we can study the impacts of parameters on the sedimentati
9、on, and results show that the temperature diffusion is conducive to the sedimentation; and the dust concentration diffusion is not conducive to the sedimentation; the larger vertical temperature turbulent exchange coefficient is more conducive to ascending in the slowly sedimentation region, even in the non-sedimentation region; and the larger vertical dust concentration turbulent exchange coefficient is more conducive to the sedimentation.Key words：Dust storm, Two-phase flow, Sedimentation, Air column entrainment model
