论文标题
一种基于Bhatnagar-krook模型的统一随机粒子方法，用于多原子气体及其与DSMC的组合
A unified stochastic particle method based on the Bhatnagar-Gross-Krook model for polyatomic gases and its combination with DSMC
论文作者
论文摘要
由于这些流中固有的多尺度和非平衡性质，因此在太空车辆周围模拟高超音速流程是具有挑战性的。为了有效地处理这种流程，最近开发了一种新型的粒子杂交方案，结合了随机粒子bhatnagar-krook（BGK）方法与直接模拟的蒙特卡洛（DSMC），但仅用于单变性气体[Fei等。 Al。，J。Comput。物理。 2021]。在这里，这项工作扩展到用于多原子气体的颗粒粒子杂交方法。在近连续体制中，采用Y. Dauvois等提出的椭圆形统计BGK模型。 al。 [欧洲。 J. Mech。 B流体，2021]具有离散水平的振动能，随机粒子BGK方法首先是按照统一随机粒子BGK（USPBGK）方案的想法建立的。在流体极限中，已证明它具有二阶时间和空间精度。然后，将带有旋转和振动能的USPBGK方案与DSMC结合使用，以构建用于多原子气体的混合方法。当前的杂种方案通过均匀松弛，1D冲击结构和2D高音流的数值测试验证，经过楔形和圆柱体。与传统的随机粒子方法相比，提出的混合方法可以以更低的计算成本获得更高的精度。因此，它是研究多尺度高音流的更有效的工具。
Simulating hypersonic flow around a space vehicle is challenging because of the multiscale and nonequilibrium nature inherent in these flows. To effectively deal with such flows, a novel particle particle hybrid scheme combining the stochastic particle Bhatnagar-Gross-Krook (BGK) method with Direct Simulation Monte Carlo (DSMC) was developed recently, but only for monatomic gases [Fei et. al., J. Comput. Phys. 2021]. Here this work is extended to the particle-particle hybrid method for polyatomic gases. In the near continuum regime, employing the Ellipsoidal Statistical BGK model proposed by Y. Dauvois, et. al. [Eur. J. Mech. B Fluids, 2021] with discrete levels of vibrational energy, the stochastic particle BGK method is first established following the idea of the unified stochastic particle BGK (USPBGK) scheme. In the fluid limit, it has been proven to be of second order temporal and spatial accuracy. Then, the USPBGK scheme with rotational and vibrational energies is combined with DSMC to construct a hybrid method for polyatomic gases. The present hybrid scheme is validated with numerical tests of homogenous relaxation, 1D shock structure and 2D hypersonic flows past a wedge and a cylinder. Compared to traditional stochastic particle methods, the proposed hybrid method can achieve higher accuracy at a much lower computational cost. Therefore, it is a more efficient tool to study multiscale hypersonic flows.
