以计算流体动力学模型(CFD)模拟的戈壁地表风沙两相流运动特征  

Simulation of movement characteristics of wind and sand two-phase flow on the gobi surface based on CFD technology

作　　者：廖承贤 王海兵 刘茜雅 李悦 Liao Chengxian;Wang Haibing;Liu Xiya;Li Yue(Key Laboratory of Aeolian Sand Control Engineering in Inner Mongolia,College of Desert Control Science and Engineering,Inner Mongolia Agricultural University,Hohhot 010011,China)

机构地区：[1]内蒙古农业大学沙漠治理学院内蒙古风沙物理与防沙治沙工程重点实验室,内蒙古呼和浩特010011

出　　处：《中国沙漠》2023年第6期71-78,共8页Journal of Desert Research

基　　金：国家自然科学基金项目(42261002、41861001)。

摘　　要：尘暴过程中沙砾质戈壁地表的风沙两相流运动,一直是风沙物理学关注的问题。但由于技术限制,野外观测及风洞实验难以捕捉大规模颗粒运动。为此,本文通过构建流体-颗粒碰撞互馈模型进行三维场域数值模拟,分析了不同砾石盖度下尘暴来流中的风沙两相流运动规律。结果表明:基于三维场流体-颗粒碰撞互馈模型修正后的求解结果能够较为准确地模拟戈壁地表风沙两相流运动过程。(1)不同来流尘暴过程,风相速度均会随砾石盖度的增大而减小,并在砾石盖度大于40%的戈壁近地表形成拜格诺焦点。相较于风相,沙相降速不明显。此外,距砾石床面4 cm以上,风沙两相速度基本保持一致。(2)当尘暴速度大于10 m·s^(-1)时,在距地1.5~2.1 m高度形成风沙两相流速度交点,交点上下表现为“风快沙慢”及“风慢沙快”现象。(3)尘暴过程中近地表沙尘浓度沿均值线呈“脉动”规律,表现为地表粉尘沉降与再释放循环过程,同时砾石盖度大小会直接影响沙尘沉积分布,当盖度大于40%时能够有效抑制沙尘释放。The two-phase flow motion of wind and sand on the gravelly gobi surface during dust storms has been a subject of much interest in wind and sand physics.However,due to technical limitations,field observations and wind tunnel experiments are difficult to capture large-scale particle motions.To this end,this paper analyzes the wind-sand two-phase flow motion during the incoming dust storm under different gravel cover by constructing a three-dimensional field numerical simulation of fluid-particle collisional mutual feedthrough model.It is found that the modified solution based on the 3D field fluid-particle collisional mutual feedthrough model can simulate the wind-sand two-phase flow motion on the gobi surface more accurately.The simulation results further show that:(1)The wind-phase velocity decreases with the increase of gravel cover for different incoming dust storm processes,and forms a Bagnold focus near the surface of the gobi where the gravel cover is greater than 40%.Compared with the wind phase,the velocity decrease in the sand phase is not obvious.In addition,above 4 cm from the gravel bed surface,the velocities of both wind and sand phases remain basically the same.(2)When the dust storm velocity is greater than 10 m·s-1,the intersection of the two phases of wind and sand flow velocity is formed in the height range of 1.5-2.1 m from the ground,and the phenomenon of“Wind is faster than sand”and“Sand is faster than wind”is manifested above and below the intersection.(3)During the dust storm process,the near-surface dust concentration shows a“pulsation”law along the mean line,which is manifested as the cycle of surface dust deposition and re-release.At the same time,the gravel coverage will directly affect the distribution of dust deposition.When the coverage is greater than 40%,it can effectively suppress dust release.

关 键 词：戈壁 砾石盖度 数值模拟 风沙两相流运动 速度交点 

分 类 号：S157[农业科学—土壤学]