论文标题
如何构建从动力学到流体状态一致的粗粒晶粒传输模型
How to build coarse-grain transport models consistent from the kinetic to fluid regimes
论文作者
论文摘要
在本文中，我们研究了如何始终如一地构建从动力学到流体状态的粗粒晶体传输模型。气体颗粒的内部能量是通过州对状态的方法来描述的。动力学方程使我们能够研究相空间中的非均匀气体混合物的传输现象。内部能量激发是使用二进制碰撞算子建模的，而气体化学过程依赖于反应性碰撞算子。我们通过Chapman-Enskog扰动溶液在Maxwellian反应方程中获得渐近流体模型。给出了物种质量，混合动量和能量的宏观保护方程，以及运输特性的表达。基本过程的可逆关系在动力学水平的粗粒模型中提出，并在直接模拟蒙特卡洛方法的碰撞算法中实现，用于求解动力学方程。此外，尊重这些可逆性关系是衍生出良好且与热力学第二定律兼容的流体模型的关键。使用统一的雕刻碰撞的粗粒粒模型，评估了动力学模拟和流体模拟之间的一致性，以模拟氮气中的冲击波。动力学模拟和流体模拟都显示出两种状态之间宏观特性和转运通量的一致性。
In this paper, we examine how to build coarse-grain transport models consistently from the kinetic to fluid regimes. The internal energy of the gas particles is described through a state-to-state approach. A kinetic equation allows us to study transport phenomena in phase space for a non-homogeneous gas mixture. Internal energy excitation is modeled using a binary collision operator, whereas the gas chemical processes rely on a reactive collision operator. We obtain an asymptotic fluid model by means of a Chapman-Enskog perturbative solution to the Boltzmann equation in the Maxwellian reaction regime. The macroscopic conservation equations of species mass, mixture momentum, and energy are given, as well as expressions of the transport properties. Reversibility relations for elementary processes are formulated in the coarse-grain model at the kinetic level and are enforced in the collision algorithm of the direct simulation Monte Carlo method used to solve the kinetic equation. Furthermore, respecting these reversibility relations is key to deriving a fluid model that is well-posed and compatible with the second law of thermodynamics. Consistency between the kinetic and fluid simulations is assessed for the simulation of a shock wave in a nitrogen gas using the uniform rovibrational collisional coarse-grain model. The kinetic and fluid simulations show consistency for the macroscopic properties and transport fluxes between both regimes.
