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A study on the initiation of saltation in the model of wind-blown sand transport considering the effect of turbulence

机译：考虑湍流效应的风吹砂运输模型中盐化在盐水模型中的研究

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摘要

Turbulence plays an important role in the transport of wind-blown sand. If the model of wind-blown sand transport considering the effect of turbulence is to be established, the influence of turbulence needs to be introduced into the four sub-processes of saltation, namely (1) aerodynamic entrainment, (2) the subsequent trajectories of saltating particles, (3) the collision of particles with the soil surface and the subsequent splashing of surface particles into the fluid stream, and (4) the modification of the wind profile through momentum transfer between the wind flow and saltating particles. In this paper, turbulence is introduced into two models predicting the first and the third sub-processes of saltation by the aerodynamic drag force and the creep velocity of surface particles respectively. The effects of turbulence on the two sub-processes are discussed. Our results show that turbulence has an important effect on aerodynamic entrainment. That is, when the wind velocity exceeds the threshold velocity, about 20% of all surface particles are unable to lift-off from the bed surface. The effect of turbulence on aerodynamic entrainment is mainly caused by large-scale turbulent motions. The model of number of lifting sand particles caused by aerodynamic drag force is modified by introducing a lift-off rate sigmadocumentclass[12pt]{minimal}usepackage{amsmath}usepackage{wasysym}usepackage{amsfonts}usepackage{amssymb}usepackage{amsbsy}usepackage{mathrsfs}usepackage{upgreek}setlength{oddsidemargin}{-69pt}egin{document}$$sigma$$end{document} (i.e., the ratio of the number of actually lifting sand particles judged by our theory to the total number of lifting sand particles judged by existing theory), which is N-a = sigma x zeta rho(mu(2)(tau)- mu(2)(c)), where sigma is defined as the lift-off rate, u(tau) is the friction wind velocity, u(c) is the threshold velocity, rho is the air density, and zeta is the empirical constant. In addition, the results show that the cumulative distribution of creep velocity under the direct action of turbulence (which can be characterized by the SGompertz distribution) has little effect on the velocity distributions of rebound particles and ejected particles.
机译：湍流在风吹砂的运输中起着重要作用。如果考虑到考虑湍流效果的风吹砂传输模型，则需要将湍流的影响引入盐化的四个子过程中，即（1）空气动力学夹带，（2）随后的轨迹盐酸颗粒，（3）颗粒与土壤表面的碰撞以及随后的表面颗粒溅入流体流，并通过风流与盐酸颗粒之间的动量转移来改变风谱。在本文中，将湍流引入到预测通过空气动力学阻力和表面颗粒的蠕变速度预测盐化的第一和第三子过程的两种模型。讨论了湍流对两个子过程的影响。我们的研究结果表明，湍流对空气动力学夹带有重要作用。也就是说，当风速超过阈值时，大约20％的所有表面颗粒都无法从床表面剥离。湍流对空气动力学夹带的影响主要是由大规模湍流运动引起的。通过引入升降速率Sigma DocumentClass [12pt] {minimal} usepackage {ammath} underpackage {amsfonts} usepackage {amsfonts} usepackage {amsymb } usepackage {amsbsy} usepackage {mathrsfs} usepackage {supmeek} setLength { oddsidemargin} {-69pt} begin {document} $$$ egma $$$ end {document}（即数字的比例实际上将通过我们理论判断为现有理论判断的提升砂颗粒总数的升降砂颗粒），其是Na = Sigma X Zeta Rho（mu（2）（tau） - mu（c）），在哪里Sigma被定义为剥离率，U（tau）是摩擦风速，U（c）是阈值速度，rho是空气密度，并且Zeta是经验常数。此外，结果表明，在湍流的直接作用下蠕变速度的累积分布（其特征在于Sgompertz分布）对回弹颗粒和喷射颗粒的速度分布几乎没有影响。

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  • 来源
    《Granular matter》 |2019年第3期|78.1-78.15|共15页
  • 作者

    Liu Li; Bo Tian-Li;

  • 作者单位

    Lanzhou Univ Minist Educ China Key Lab Mech Disaster & Environm Western China Lanzhou 730000 Gansu Peoples R China|Lanzhou Univ Coll Civil Engn & Mech Dept Mech & Engn Sci Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Minist Educ China Key Lab Mech Disaster & Environm Western China Lanzhou 730000 Gansu Peoples R China|Lanzhou Univ Coll Civil Engn & Mech Dept Mech & Engn Sci Lanzhou 730000 Gansu Peoples R China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Wind-blown sand; Turbulence; Creep velocity; Splashing process;

    机译：风吹沙;湍流;蠕变速度;溅过程;

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