自由流区近壁蒸发及未蒸发颗粒的热泳分析

本文给出了自由分子流区作用在壁面附近蒸发及未蒸发颗粒上的热泳力的分析结果.分析中气体分子在壁面和颗粒表面处均假定为部分镜反射和部分漫反射.分析表明,作用在近壁颗粒上的热泳力不仅依赖于气体中的温度梯度,还和气体的压力以及壁面与气体温度比有关.颗粒表面的温度和镜反射分数对作用于未蒸发颗粒的热泳力没有影响,但明显影响作用于蒸发颗粒的热泳力.研究表明,近壁效应及蒸发对颗粒热泳的附加影响是不容忽视的.

THERMOPHORESIS OF A NEAR-WALL NONEVAPORATING OR EVAPORATING PARTICLE FOR THE FREE-MOLECULE REGIME

Analytical results are presented concerning the thermophoretic force acting on a spherical nonevaporating or evaporating particle suspended near a planar wall for the free-molecule regime. A combined specular and diffuse reflection at the wall and at the particle surface is included in the analysis. It has been shown that the thermophoretic force acting on the near-wall particle depends not only on the temperature gradient or heat flux within the bulk gas) but also on the gas pressure and wall/gas temperature ratio. The temperature and specular reflection fraction at the particle surface do not affect the thermophoretic force for a nonevaporating particle, but they thect the thermophoretic force acting on an evaporating particle. The present analysis shows that the influence of the near-wall effect and the evaporation on the particle thermophoresis can not be ignored.