稳态风沙流中沙粒体积浓度的模型分析

A Model of Particle Volume Concentration in Steady Windblown Sand Movement

本文建立了一个简单有效的稳态风沙流中沙粒体积浓度的数学模型,包括3个部分:稳态风沙流的风速廓线描述、跃移沙粒轨迹的计算、床面沙粒起跳速度分布的描述。利用已知实验的风速廓线作为气流速度场输入参数,跃移沙粒轨迹的计算主要考虑重力和拖曳力,基于体积观点的床面起跳沙粒的水平速度和垂直速度概率密度分布函数分别采用正态分布和指数分布函数来描述。根据稳态风沙流中运动沙粒的动态平衡特征可推导计算沙粒体积浓度。计算的沙粒体积浓度与风洞实验结果基本一致,说明本模型有较好的预测能力。

A simple and available mathematical model is developed for particle volume concentration in steady windblown sand movement,which includes three sections:wind velocity description,calculation of saltating particle trajectory and the description of particle ejected velocity distribution.In the model,the experimental wind velocity profile is used for the calculation of wind velocity,and the particle gravity and drag force are mainly considered for the calculation of particle trajectory.Based on the volume view,the probability density distributions of horizontal and vertical lift-off particle velocities are expressed by normal function and exponential function,respectively.Then the particle volume concentration can be deduced according to the dynamic equilibrium of particle motion in steady windblown sand movement.The result shows that the calculated particle volume concentration is consistent with the experimental results in wind tunnel,this reflects that the present model can provide a better prediction for the particle volume concentration in steady windblown sand movement.