| 基于激光垂直照射沙床面的风成沙波纹二维形态特征分析 |
| |
| 引用本文： | 常菊,肖锋军,董治宝,陈颢,马慧榕.基于激光垂直照射沙床面的风成沙波纹二维形态特征分析[J].中国沙漠,2021,41(5):33-42. |
| |
| 作者姓名： | 常菊 肖锋军 董治宝 陈颢 马慧榕 |
| |
| 作者单位： | 陕西师范大学 地理科学与旅游学院，陕西 西安 710119 |
| |
| 基金项目： | 国家自然科学基金项目(42071009);中国博士后科学基金项目(2017M623115);中央高校基本科研业务费专项资金项目(GK202103141);陕西省自然科学基础研究计划项目(2018JQ4028) |
| |
| 摘 要： | 风成沙波纹因其规则的波浪形几何图案吸引着研究者的兴趣，但是对其发育过程的认识还比较薄弱。原因之一就是缺少高精度和高分辨率的沙波纹形态动态测量方法。传统的风成沙波纹形态动态测量方法采用的倾斜光源照射方式忽略了沙波纹脊线高度和走向的变化，会导致沙波纹高度测量错误和形态变形。本研究建立的激光片光源垂直照射沙波纹表面的方式纠正了这一问题，并分析了沙波纹形态及其参数随时间的变化规律。结果表明：（1）沙波纹发育形成过程的初始形成阶段、增长阶段和稳定阶段的时长都随风程长度的增加呈减小趋势，且风程长度越短沙波纹的发育进程越滞后，形成 “倒游现象”。（2）沙波纹的波高和波长都随时间先快速增大然后趋于稳定，而且波高增长速度随风程长度增加而增大。稳定阶段沙波纹平均高度和波长呈现随风程长度的增加而增大的趋势。（3）沙波纹指数、迎风坡指数和背风坡指数都随时间先快速减小然后基本保持不变，服从指数函数分布。稳定阶段平均沙波纹指数随风程长度增加而减小。（4）沙波纹移动速度总体上随高度增大而减小，平均移动速度随时间按幂函数减小，而且在风沙流未饱和时平均移动速度总体上呈随风程长度增加而减小的趋势。可见，风程长度是沙波纹定量中不可忽略的一个因素。
|
| 关 键 词： | 沙波纹形态 波长 风程效应 风洞 |
| 收稿时间： | 2021-01-26 |
| 修稿时间： | 2021-04-13 |
Research of two-dimensional morphological characteristics of aeolian sand ripples by laser vertically irradiating the sand bed |
| |
| Ju Chang,Fengjun Xiao,Zhibao Dong,Hao Chen,Huirong Ma.Research of two-dimensional morphological characteristics of aeolian sand ripples by laser vertically irradiating the sand bed[J].Journal of Desert Research,2021,41(5):33-42. |
| |
| Authors: | Ju Chang Fengjun Xiao Zhibao Dong Hao Chen Huirong Ma |
| |
| Institution: | School of Geography and Tourism，Shaanxi Normal University，Xi’an 710119，China |
| |
| Abstract: | Aeolian sand ripple attracts people's attention because of its regular wavy geometric pattern， but its formation process is still lack of in-depth understanding. The lack of high-precision and high-resolution measurement method of sand ripple profile is one reason. The laser sheet is inclined at some angle to the sand bed in the traditional measurement method. It will cause the inaccurate measurement of height and the deformation of sand ripple profile. In this study， we correct the problem by irradiating the sand bed vertically and analyze the influence of fetch length on the evolution of geometric parameters with time. The results show that： （1） The durations of the initial formation stage， the growth stage and the stable stage of the sand ripple decrease with the increase of the fetch length， and the shorter the fetch length， the slower the development process of the sand ripple， forming the "backward phenomenon". （2） The height and wavelength of sand ripple increase rapidly with time at first and then are gradually become stable in the end. The growth rate of ripple height increases with the increase of fetch length. The mean ripple height and wavelength increase with fetch length. （3） The ripple indexes， windward indexes and leeward indexes decrease with time following an exponential law. At the stable stage of the sand ripples， the mean ripple index decreases with fetch length. （4） The propagation velocity of sand ripple shows a decreasing trend with ripple height. The mean propagation velocity decreases according to a power law with respect to time， and it decreases with fetch length when saturated sand flux is not reached. Therefore， the fetch length is a key factor in the study of sand ripple. |
| |
| Keywords: | sand ripple profile wavelength fetch effect wind tunnel |
|
| 点击此处可从《中国沙漠》浏览原始摘要信息 |
| 点击此处可从《中国沙漠》下载免费的PDF全文 |
