摘要
Atmospheric turbulence which induced by wind shear and/or convection is non-uniform anisotropic flows of high Reynolds and Rayleigh number[1].According to the mechanism of turbulence generation,atmospheric boundary-layer stratification can be classified into neutral,unstable(convective)and stable[2].Observations show that sandstorms and wind-blown sand mostly occur under unstable stratifications from afternoon to early evening[3].As the surface absorbs the solar radiation,the surface temperature increases and vertical convection develops,which enhances the momentum exchange between the upper and lower layers and hence increases the near surface wind speed and shear stress[4].
在干旱半干旱地区风沙运动频繁发生,大气多为不稳定层结条件.目前大多数关于风沙运动的研究主要基于中性或近中性层结条件,这与自然实际存在偏差.因此,本文使用大涡模拟耦合拉格朗日粒子追踪方法建立了考虑大气层结的风沙运动模型.结果表明,当风速接近颗粒起动阈值时,不稳定层结对输沙率有显著影响,但随着风速的增大,这种影响逐渐减弱.为了更好地表征层结稳定度对输沙率的影响,本文提出了有效地表剪切应力参数,该参数包含颗粒起动阈值和地表剪切应力分布的信息.分析表明,有效地表剪切应力的大小与初始风速和对流速度尺度有关,且与输沙率满足线性关系.
作者
Panli He
Jie Zhang
Hans J.Herrmann
Ning Huang
何盼莉;张洁;Hans J.Herrmann;黄宁(Key Laboratory of Mechanics on Disaster and Environment in Western China,Lanzhou University,Lanzhou 730000,China;College of Civil Engineering and Mechanics,Lanzhou University,Lanzhou 730000,China;Department 403,Rocket Force University of Engineering,Xi’an 710025,China;Laboratoire de Physique et Mécanique des Milieux Hétérogènes,École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris,Paris 75005,France;Departamento de Física,Universidade do Ceará,Fortaleza 60020-181,Brazil)
基金
supported by the State Key Program of National Natural Science Foundation of China(41931179)
the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK020109 and 2019QZKK020611)
the Major Science and Technology Project of Gansu Province(21ZD4FA010)
the National Natural Science Foundation of China(11772143)
the Fundamental Research Funds for the Central Universities(lzujbky2020-cd06)
Scientific and Technological Research and Development Plan of China Railway Urumqi Bureau Group Co.LTD(WLMQ-KGHZGS-HRTLGGB-2020-0031)
the Youth Fund of PLA Rocket Force University of Engineering(2021QN-B029)。
