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Study on Gas Mixture in Micro Channel

微通道内气体混合物的研究

基本信息

批准号：
17560151
负责人：
HYAKUTAKE Toru
金额：
$ 2.02万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17560151/
关键词：
Rarefied Gas Dynamics Accommodation Coefficient DSMC method Molecular Dynamics method Micro Channel Gas Mixture

项目摘要

To investigate flow of gas mixtures through micro channel in detail, the tangential momentum accommodation coefficients of each species for gaseous mixtures were determined by analyzing the Couette flow problem of a slightly rarefied gas between two walls. The molecular dynamics (MD) method for the interaction of gas molecule with the wall surface was combined with the DSMC method for the motion of gas molecules. These obtained accommodation coefficients were applied for the flow of gas mixture through the micro channel as the Maxwell-type boundary conditions, and influence of the surface with adsorbates and the gas concentration on the flow rate of the micro channel was examined. The simulation results showed that the velocity slip and the accommodation coefficients for gas mixtures differ from that for a single gas. The differences of the molar concentration of gas mixtures and wall characteristics leaded to variations of the flow rate in the channel. Furthermore, the scattering behaviors of nitrogen molecules reflected at a platinum surface were studied by the molecular dynamics method for the gas-surface interaction. The platinum surface was assumed to physically adsorb xenon molecules. Distributions of molecular velocities after reflection were obtained for the impinging molecules with specified velocities within a small range. The scattering distribution showed a bimodal behavior consisting of diffuse reflection and a distribution shifting to the velocity distribution of the impinging molecules. Comparison between the present scattering distribution and the Cercignani-Lampis-Lord scattering kernel showed large differences. A simple scattering kernel using a bimodal distribution was proposed assuming mutual independence of distributions in each velocity component and was compared favorably to the present scattering distribution. In addition, the scattering kernel of the rotational energy of the molecule was discussed.

为了详细研究气体混合物在微通道中的流动，通过分析微稀薄气体在两壁间的Couette流动问题，确定了各种气体混合物的切向动量调节系数。将气体分子与壁面相互作用的分子动力学(MD)方法与气体分子运动的DSMC方法相结合。将得到的调节系数作为麦克斯韦边界条件应用于气体混合物在微通道中的流动，考察了吸附表面和气体浓度对微通道流量的影响。模拟结果表明，混合气体的速度滑移和调节系数不同于单一气体。混合气体的摩尔浓度和壁面特性的不同导致了通道内流量的变化。此外，用气体-表面相互作用的分子动力学方法研究了氮分子在铂表面反射的散射行为。铂表面被认为是物理上吸附了氙气分子。得到了在小范围内具有特定速度的入射分子反射后的分子速度分布。散射分布呈现出双峰行为，包括漫反射和向入射分子速度分布移动的分布。目前的散射分布与Cercignani-Lampis-Lord散射核的比较显示出很大的差异。在假设每个速度分量的分布相互独立的前提下，提出了一个采用双峰分布的简单散射核，并与现有的散射分布进行了比较。此外，还讨论了分子转动能的散射核。