CDS&E: AST: Collaborative Research: Computational science in support of space missions: plasma turbulence modeling on geodesic meshes

在太阳风和其他天体物理环境中的原位和远程观测表明，等离子体总是具有各向异性的温度。这需要非理想磁流体动力学（MHD），但到目前为止，还没有一致的方法来模拟必要的物理。太阳物理学中最重要的悬而未决的问题是解释日冕的异常高温，从而解释太阳风的起源。即将到来的观测将提供丰富的新信息，但解释可能会发现目前的理论相当不足。该项目将超越MHD近似，使用最复杂的计算算法并结合研究团队的独特优势。为分析太阳活动而开发的计算工具将更好地了解太阳风暴是如何产生的，从而提高预测空间天气的能力。研究团队积极参与计算物理的教学和传播，对劳动力发展产生重大影响。等离子体理论的最新进展提供了包含各向异性压力的流体层次的闭包，将线性朗道阻尼重现到所需的任何精度，并展示了流体和无碰撞动力学描述的收敛性。这项工作将把日冕和内日球层等离子体的高级描述整合到波传播、湍流传输和各向异性加热的模型中。它将使Chew-Goldberger-Low （CGL）方程（包括Hall项）能够在基于物理的湍流闭包的自适应球形网格上求解。这涉及三个高度创新的任务：1)Hall-CGL方程的正确处理；2)球面网格自适应细化技术的发展；3)紊流的弱可压缩模型，该模型能够基于物理估计具有各向异性压力分布的等离子体中各向异性热传导的输运系数。由此产生的代码将把天体物理学和空间科学界带到天体物理等离子体建模的下一个复杂水平。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In situ and remote observations in the solar wind and other astrophysical environments reveal that the plasma invariably possesses anisotropic temperatures. This requires non-ideal magnetohydrodynamics (MHD), but so far there has been no consistent approach to modeling the necessary physics. The most significant open question in heliophysics is to explain the extraordinarily high temperature of the solar corona and hence the origin of the solar wind. Forthcoming observations should provide a wealth of new information, but interpretation is likely to find current theory considerably wanting. This project will go beyond the MHD approximation using the most sophisticated computational algorithms and combining the unique strengths of the research team. The calculational tools developed to analyze solar activity will yield a better understanding of how solar storms arise and thus enhance predictive space weather capabilities. The research team is heavily involved in the teaching and dissemination of computational physics with significant workforce development impact.Recent advances in plasma theory provide closures of the fluid hierarchy incorporating anisotropic pressures, reproducing linear Landau damping to any desired precision, and demonstrating convergence of the fluid and collisionless kinetic descriptions. This work will integrate an advanced description of the coronal and inner heliosphere plasma into models of wave propagation, turbulence transport, and anisotropic heating. It will enable solution of the Chew-Goldberger-Low (CGL) equations, including a Hall term, on adaptive, spherical meshes with physics-based turbulent closures. This involves three highly innovative tasks: 1) a correct treatment of the Hall-CGL equations; 2) development of adaptive mesh refinement for spherical meshes; 3) a weakly compressible model for turbulence which enables a physics-based estimate of the transport coefficients for anisotropic thermal conduction in plasmas with anisotropic pressure distributions. The resulting code will take the astrophysics and space science communities to the next level of sophistication in modeling astrophysical plasmas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.