论文标题
多原子气体的动力学模型还原
Reduced kinetic model of polyatomic gases
论文作者
论文摘要
多原子气体的动力学模型通常解释了两粒子分布函数水平上的内部自由度。但是，接近流体动力学极限，内部（旋转）自由度往往仅以旋转动能密度很好地表示。我们通过在单粒子分布函数的级别上以对流 - 延伸 - 重新解释方程的级别在单粒子分布函数的水平上增强椭圆形统计BGK（ES-BGK）模型来考虑旋转能。该减少模型尊重H定理，并恢复多原子气体作为其宏观极限的可压缩流体动力学。由于多原子气模型的要求，ES-BGK模型的这种扩展不仅具有正确的特定热比，而且还允许三个独立的可调传输系数：导热率，剪切粘度和块状粘度。我们通过晶格Boltzmann方法实施说明了模型的有效性。
Kinetic models of polyatomic gas typically account for the internal degrees of freedom at the level of the two-particle distribution function. However, close to the hydrodynamic limit, the internal (rotational) degrees of freedom tend to be well represented just by rotational kinetic energy density. We account for the rotational energy by augmenting the Ellipsoidal-statistical BGK (ES-BGK) model, an extension of the Bhatnagar-Gross- Krook (BGK) model, at the level of the single-particle distribution function with an advection-diffusion-relaxation equation for the rotational energy. This reduced model respects the H theorem and recovers the compressible hydrodynamics for polyatomic gases as its macroscopic limit. As required for a polyatomic gas model, this extension of the ES-BGK model has not only correct specific heat ratio but also allows for three independent tunable transport coefficients: thermal conductivity, shear viscosity, and bulk viscosity. We illustrate the effectiveness of the model via a lattice Boltzmann method implementation.
