AI 中文总结
研究如何准确模拟无碰撞空间等离子体，通过引入渐近保持策略扩展多模型层次结构，将双物种五矩流体与理想MHD求解器耦合，确保模型界面一致性，经磁重联模拟证明了完全耦合框架的有效性和鲁棒性。
AI 中文摘要
准确模拟无碰撞空间等离子体需要捕捉小尺度动力学效应，同时保持全局尺度模拟的计算可行性。传统多尺度方法常依赖局部磁流体动力学（MHD）-粒子在单元格（PIC）耦合或动态模型层次结构。本文通过引入一种渐近保持（AP）策略，扩展了一个既定的、从完全动力学的弗拉索夫描述到流体模型的自适应多模型层次结构，该策略将双物种五矩流体描述与理想MHD求解器耦合。这种耦合是实现高效全局模拟的关键最后一步，因为非理想区域的动力学尺度物理完全由层次结构中更精细的模型处理。动力学描述自然地求解麦克斯韦方程组，从而捕捉MHD动力学中不存在的快速等离子体波、振荡和光波。为了在不牺牲计算效率的情况下解决这种差异，我们的AP框架将这些快速动力学无缝地投影到缓慢的MHD动力学上，确保模型界面处的严格一致性。我们详细介绍了AP双流体公式、可变耦合界面及其在外部框架中的集成。最后，我们通过磁重联模拟证明了从动力学到理想MHD的完全耦合框架的有效性和鲁棒性。
英文摘要
Accurately modeling collisionless space plasmas requires capturing small-scale kinetic effects while keeping global-scale simulations computationally tractable. Traditional multiscale approaches often rely on localized magnetohydrodynamics (MHD)-particle-in-cell (PIC) coupling or dynamic model hierarchies. In this work, we extend an established, adaptive multi-model hierarchy spanning from fully kinetic Vlasov descriptions to fluid models by introducing an asymptotic-preserving (AP) strategy that couples a two-species, five-moment fluid description with an ideal MHD solver. This coupling is the final critical step toward enabling efficient global simulations because the kinetic-scale physics in nonideal regions is entirely handled by finer models in the hierarchy. Kinetic descriptions natively solve Maxwell's equations and thus capture fast plasma waves, oscillations, and light waves, which are absent in the MHD dynamics. To address this difference without sacrificing computational efficiency, our AP framework seamlessly projects these fast dynamics onto the slow MHD dynamics, ensuring rigorous consistency at the model interfaces. We detail the AP two-fluid formulation, the variable-coupling interface, and its integration into external frameworks. Finally, we demonstrate the validity and robustness of the fully coupled framework, from kinetics to ideal MHD, through magnetic reconnection simulations.
Comments21 pages, 10 Figures
