Uncertainty quantification in rarefied dynamics of molecular gas: rate effect of thermal relaxation
Uncertainty quantification in rarefied dynamics of molecular gas: rate effect of thermal relaxation
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DOI：
10.1017/jfm.2021.338
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发表时间：
2021-05
影响因子：
3.7
通讯作者：
Qi Li;Jianan Zeng;Wei-Jen Su;L. Wu
中科院分区：
文献类型：
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作者：
Qi Li;Jianan Zeng;Wei-Jen Su;L. Wu
分子气体的热导率由平动部分和内部部分组成。虽然在连续流中，总热导率本身足以描述热传递，但在稀薄气体流中，它们需要根据均质系统中平移和内部热通量的弛豫率单独建模。本文致力于量化这些弛豫率如何影响稀薄气体动力学。Wu等人（J. Fluid Mech.，第763卷，2015年，pp. 24-50）适用于恢复热通量的松弛，这是通过直接模拟蒙特卡罗方法进行验证。然后，Wu等人的模型，该方法具有调节弛豫速率的自由度，可用于研究正激波、麦克斯韦妖驱动的蠕变流和热蒸腾等问题中热弛豫的速率效应。研究发现，即使在总热导率一定的情况下，热流松弛率对稀薄气体流动的影响也是显著的。
Abstract The thermal conductivity of a molecular gas consists of the translational and internal parts. Although in continuum flows the total thermal conductivity itself is adequate to describe the heat transfer, in rarefied gas flows they need to be modelled separately, according to the relaxation rates of translational and internal heat fluxes in an homogeneous system. This paper is dedicated to quantifying how these relaxation rates affect rarefied gas dynamics. The kinetic model of Wu et al. (J. Fluid Mech., vol. 763, 2015, pp. 24–50) is adapted to recover the relaxation of heat fluxes, which is validated by the direct simulation Monte Carlo method. Then the model of Wu et al., which has the freedom to adjust the relaxation rates, is used to investigate the rate effects of thermal relaxation in problems such as the normal shock wave, creep flow driven by Maxwell's demon and thermal transpiration. It is found that the relaxation rates of heat flux affect rarefied gas flows significantly, even when the total thermal conductivity is fixed.