基于数字化轨迹的跃移粒子群速度剖面研究  

Research on velocity profiles of saltating particles based on their digital trajectories

作　　者：蒋缠文 董治宝 罗万银 钱广强 张正偲 逯军峰 王晓艳 Chanwen Jiang;Zhibao Dong;Wanyin Luo;Guangqiang Qian;Zhengcai Zhang;Junfeng Lu;Xiaoyan Wang(College of Environment and Life Sciences/Shaanxi Key Laboratory of River Wetland Ecology and Environment,Weinan Normal University,Weinan 714000,Shaanxi,China;College of Geography and Tourism,Shaanxi Normal University,Xi'an 710119,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]渭南师范学院环境与生命科学学院/陕西省河流湿地生态与环境重点实验室,陕西渭南714000 [2]陕西师范大学地理科学与旅游学院,陕西西安710119 [3]中国科学院西北生态环境资源研究院,甘肃兰州730000

出　　处：《中国沙漠》2024年第6期231-239,共9页Journal of Desert Research

基　　金：国家自然科学基金项目(41901012,41971014,41930640);中国博士后科学基金项目(2019M663615);中国科学院沙漠与沙漠化重点实验室开放课题(KLDD-2021-005);陕西省教育厅重点实验室项目(22JS017)。

摘　　要：研究跃移运动时,速度是一个重要参数。采用高速摄影技术在风洞中获得了松散沙面上跃移沙粒在上升段和降落段的平均速度垂直剖面。结果表明:垂直方向上的颗粒湍流强度高于水平方向1~2个数量级,造成颗粒速度在水平方向上很好地服从正态分布,而在垂直方向上则较为分散且范围较窄(0~1 m·s^(-1))。同一高度处,降落段的平均水平速度是上升段的1.6~1.8倍,而降落段的垂直速度则略小于上升段。两段的相对平均水平速度(v_(x)/√gd,g为重力加速度,d为颗粒粒径)均与相对高度(z/Z,z为距床面高度,Z为边界层厚度)的平方根以及相对风速(u_(*)/u_(*ti),u_(*)为摩阻风速,u_(*ti)为冲击阈值)呈正比。上升段和降落段的平均垂直速度总体上均呈现随高度略微增加的趋势。上升段的平均垂直速度略高于降落段。平均垂直速度分布模式以及随高度变化特征的潜在机制需要通过进一步研究来阐明。Velocity serves as a crucial parameter in the study of saltation motion.We utilized high-speed photography technology to acquire the vertical profiles of the average velocities of saltating sand grains on a loose sand surface during the ascending and descending phases within a wind tunnel.The outcomes reveal that the particle turbulence in the vertical direction is one to two orders of magnitude greater than that in the horizontal direction,inducing the particle velocities to conform well to a normal distribution in the horizontal direction.Meanwhile,they are more dispersed and have a narrower range(approximately 0-1 m·s^(-1))in the vertical direction.At the identical height,the average horizontal velocity in the descending phase is approximately 1.6-1.8 times that in the ascending phase,whereas the vertical velocity in the descending phase is marginally smaller than that in the ascending phase.The relative average horizontal velocities(v_(x)/√gd,where g represents the gravitational acceleration and d denotes the particle diameter)in both phases are proportional to the square root of the relative height(z/Z,where z is the height from the bed surface and Z is the thickness of the boundary layer)and the relative wind speed(u_(*)/u_(*ti),where u_(*) stands for the friction wind speed and u_(*ti) is the impact threshold).The average vertical velocities in both the ascending and descending phases typically exhibit a slightly ascending trend with height.The average vertical velocity in the ascending phase is slightly higher than that in the descending phase.The underlying mechanisms of the average vertical velocity distribution patterns and the characteristics of variation with height necessitate further investigation for clarification.

关 键 词：风沙跃移 平均速度 垂直变化 数字化轨迹 高速摄影技术 

分 类 号：X169[环境科学与工程—环境科学]