论文标题
统一的气体运动波粒方法IV：多物种气体混合物和血浆传输
Unified Gas-kinetic Wave-Particle Method IV: Multi-species Gas Mixture and Plasma Transport
论文作者
论文摘要
在本文中，我们将统一的气动波颗粒（UGKWP）方法扩展到多物种气体混合物和多尺度等离子体传输。该方案的构建基于对网格大小和时间步量表的直接建模，而当地单元格的knudsen编号决定了流体物理。所提出的方案具有多尺度和渐近复杂性降低特性。多尺度的特性意味着，根据细胞的knudsen数字，该方案可以捕获稀疏流动型中的非平衡流体物理，并保留连续性方案中的渐近欧拉，Navier-Stokes和Magnetodrodynalnical限制。渐近复杂性降低了性质，这意味着该方案的总自由度会自动降低，因为细胞的knudsen数量降低。在连续体制中，该方案自动从动力学求解器转换为流体动力求解器。在UGKWP中，显微镜速度分布的演变与宏观变量的演化结合，粒子的演化以及宏观通量是从累积的时间到从运动模型方程式的时间步长的时间到时间步长的。 对于等离子体传输，当前方案提供了从稀有状态中细胞（PIC）方法中的粒子（PIC）方法的平滑过渡，再到连续体状态中的磁性水力动力学（MHD）求解器。在连续限制中，UGKWP方法的单元格大小和时间步骤不仅限于平均自由路径和平均碰撞时间。在高度磁化的状态下，细胞的大小和时间步骤不受Debye长度和等离子体转基因周期的限制。通过多种流程中的数值测试来验证该方案的多尺度和渐近复杂性。
In this paper, we extend the unified gas-kinetic wave-particle (UGKWP) method to the multi-species gas mixture and multiscale plasma transport. The construction of the scheme is based on the direct modeling on the mesh size and time step scales, and the local cell's Knudsen number determines the flow physics. The proposed scheme has the multiscale and asymptotic complexity diminishing properties. The multiscale property means that according to cell's Knudsen number the scheme can capture the non-equilibrium flow physics in the rarefied flow regime, and preserve the asymptotic Euler, Navier-Stokes, and magnetohydrodynamics limit in the continuum regime. The asymptotic complexity diminishing property means that the total degree of freedom of the scheme automatically decreases as cell's Knudsen number decreases. In the continuum regime, the scheme automatically degenerates from a kinetic solver to a hydrodynamic solver. In UGKWP, the evolution of microscopic velocity distribution is coupled with the evolution of macroscopic variables, and the particle evolution as well as the macroscopic fluxes are modeled from the time accumulating solution up to a time step scale from the kinetic model equation. For plasma transport, current scheme provides a smooth transition from particle in cell (PIC) method in the rarefied regime to the magnetohydrodynamic (MHD) solver in the continuum regime. In the continuum limit, the cell size and time step of the UGKWP method is not restricted to be less than the mean free path and mean collision time. In the highly magnetized regime, the cell size and time step are not restricted by the Debye length and plasma cyclotron period. The multiscale and asymptotic complexity diminishing properties of the scheme are verified by numerical tests in multiple flow regimes.
