Dissipation and Kinetic Physics of Astrophysical Turbulence

湍流是与流体、气体和等离子体相关的基本物理现象之一。在天体物理现象中，湍流提供了一种有效的能量、动量和粒子传输机制，因此在天体物理对象的动力学中起着关键作用。由于可以从航天器上进行测量，太阳风已经成为研究湍流的独特实验室。因此，利用观测、理论和计算工具的组合来研究太阳风湍流已经做出了相当大的努力。虽然对这一现象的基本物理学的理解已经有了很大的进步，但仍然有大量的关键问题没有得到回答。该项目计划使用Blue Waters Leadance类计算系统进行开创性的大规模模拟，以研究能量如何在太阳风中级联并最终消散。这项研究将极大地促进对湍流的认识，并将代表着对太阳风湍流进行逼真模拟的努力的一个非常重要的里程碑。此外，该项目的结果将引起从事太阳风等离子体、日冕等离子体和等离子体天体物理工作的广大研究人员的极大兴趣。总体而言，这个项目是一个更大的基础科学研究流的一部分，这对国家科学基金会的任务至关重要。一个特别具有挑战性的问题，也是这项提议的焦点，是磁流体动力学(MHD)湍流将能量级联到动力学尺度上会发生什么。这个问题不仅与基本的等离子体物理学有关，而且与太阳风和太阳电晕加热这一非常重要的问题直接相关，这个问题对于理解太阳-地球相互作用至关重要，但到目前为止还没有一个确凿的解决方案。这项研究将克服现有方法的许多局限性，并将提供其他技术无法获得的关于影响和参数制度的补充信息。计划在Blue Waters上进行的3D模拟将达到MHD尺度，同时保留动力学效果，并将提供对研究界提出的许多关键问题的一瞥。此外，模拟将能够与航天器观测进行详细比较，并探索同时出现在模拟中的竞争过程的作用。这些模拟中的丰富信息类似于从许多航天器飞行任务中收集的数据，需要整个社区进行分析。因此，该项目产生的模拟数据将提供给社区进行分析。

Turbulence is one of the fundamental physical phenomena associated with fluids, gasses, and plasmas. In astrophysical phenomena, turbulence provides a mechanism of efficient energy, momentum, and particle transport thus playing a key role in the dynamics of astrophysical objects. The solar wind has served as a unique laboratory for studies of turbulence due to the availability of measurements from spacecraft. Accordingly, considerable effort has been made to study solar wind turbulence using a combination of observational, theoretical, and computational tools. While understanding of the basic physics of this phenomenon has advanced greatly, a significant number of key questions remain unanswered. This project proposes to use the Blue Waters leadership class computing system to execute ground-breaking large scale simulations to investigate how energy cascades and is ultimately dissipated in the solar wind. This study will significantly advance the state of knowledge of turbulence and will represent a very important milestone in the efforts to perform realistic modeling of solar wind turbulence. Additionally, the project results will be of great interest to a wide community of researchers working on solar wind plasma, coronal plasma, and plasma astrophysics. Overall, this project is part of a larger stream of fundamental scientific research, which is central to the mission of the NSF.One particularly challenging question, which is the focus of this proposal, is what happens to the energy that is cascaded to kinetic scales by magnetohydrodynamic (MHD) turbulence. This question is not only of basic plasma physics interest, but is also directly related to the very important problem of solar wind and solar corona heating that is crucial to understanding of the Sun-Earth interaction, but has so far eluded a conclusive solution. This study will overcome many of the limitations of existing approaches and will provide complementary information covering effects and parameter regimes inaccessible to other techniques. The planned 3D simulations on Blue Waters will reach into the MHD scales while retaining kinetic effects and will provide a glimpse into many of the crucial questions posed by the research community. Additionally, the simulations will enable detailed comparison with spacecraft observations and exploration of the role of competing processes that are simultaneously present in the simulations. The wealth of information in these simulations is akin to data collected from many spacecraft missions and warrants analysis from the community at large. As such, the simulation data resulting from the project will be made available to the community for analysis.