跃移雪颗粒运动特性的数值模拟研究  

Numerical Simulation on Movement Characteristics of Saltating Snow Particles

作　　者：周晅毅[1] 刘长卿[1] 顾明[1] 

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092

出　　处：《同济大学学报（自然科学版）》2013年第4期522-529,546,共9页Journal of Tongji University:Natural Science

基　　金：国家自然科学基金(51278368);科技部国家重点实验室基金(SLDRCE08-A-03);中央高校基本科研业务费专项资金;教育部留学回国人员科研启动基金

摘　　要：运用拉格朗日方法,根据雪颗粒的运动机理,对单个跃移颗粒运行轨迹进行了数值计算.同时,结合颗粒的受力特征,对影响其运动的一些参数,如粒子直径、摩擦速度和颗粒密度等进行了分析.结果表明,随着雪颗粒直径或雪粒密度的增大,粒子竖向受力与重力之比减小,粒子的跃移高度则随之增大;而当粒子起跳速度不同时,水平方向受力与重力之比的变化规律也表现不同,进而影响其水平方向的跃移长度.基于经验公式,建立了雪面侵蚀质量通量与跃移粒子数目之间的关系,计算了雪颗粒质量传输率,并与经典文献的计算方法进行了比较.结果显示,随着雪颗粒直径和摩擦速度的增大,粒子质量传输率随之增大;随着阈值摩擦速度增大,粒子质量传输率随之减小.所得计算结果与Iversen经验公式吻合较好.According to the movement mechanism of snow particles, the numerical simulation on a single saltating particle＇s trajectory was carried out with the Lagrange method. At the same time, an analysis was made of some parameters including the particle diameter, the friction velocity and particle density in accordance with the characteristics of forces on particles. The results show that as the snow particle diameter or particle density increases, the ratio of particle vertical force to gravity decreases, but the particle saltation height increases. The ratio of horizontal force to gravity varies with the particle＇ s liftoff velocity, thereby affecting its horizontal saltation length. Based on an empirical formula, the relationship between the mass flux of snow surface erosion and the number of saltation particles is established to calculate the mass transport rate of snow particles. And the calculation results are compared with the calculated results by a classical empirical formula. The comparison shows that the particle mass transport rate increases with the growth of snow particle diameter and friction velocity, but it decreases while the threshold friction speeds up. The present results agree well with those by Iversen＇ s empirical formula.

关 键 词：拉格朗日方法 跃移轨迹 质量传输率 数值模拟 

分 类 号：TU312[建筑科学—结构工程]