水平表面上多机理作用下气溶胶沉积特性数值分析

采用离散随机模型模拟了水平表面上气溶胶粒子沉积的微观过程.基于随机游走方法,求解了微粒在布朗扩散和外场迁移两种输运机制耦合作用下的运动轨迹,分析了沉积物形结构特征与微粒输运机制间的作用关系,并讨论了不同沉积机制和粒径分布下的表面沉积水平.结果表明,低Pe数下沉积物形态呈现疏松的粉尘絮团结构,而在高Pe数下沉积物则表现出较为紧密的堆积结构.不同沉积机制下粒子沉积形态结构的差异取决于微粒运动轨迹的随机强度;水平表面最大沉积微粒数存在一上限值,且与微粒输运机制和粒径分布均有关.

Numerical analysis of aerosol deposition onto horizontal surfaces by combined mechanisms

A discrete stochastic model was developed to simulate deposition of aerosol particles onto horizontal solid surfaces. Lattice walk method was employed to solve particle-transport-equation, which allowed obtaining the trajectory of particle motion by combination of migration by external field and diffusion in the calculation domain. The local structures of deposited particles forming dust layer, the relationship between structure of dust layer and mechanisms of particle transport, and the number of the particles attached to a horizontal surface were investigated. The results showed that for low values of Peclet number, when diffusion was a controlling mechanism of aerosol transport, dust layers might exhibit more open and looser structures, while the layer structures were dense and tight at high values of Peclet number. Differences of aerosol deposition morphology between different transport mechanisms were caused by different random intensities of particle motion. Additionally, there was an upper limit of the maximum number of particles attached to the surface, and it strongly depended on particle transport mechanisms and size distributions.