SHINE: Faster Boundary-Conforming Simulations of Solar Convection on Unstructured Grids

SHINE：非结构化电网上太阳对流的更快边界一致模拟

• 批准号: 2310372
• 负责人: Chunlei Liang
• 金额: $ 39.94万
• 依托单位: Clarkson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310372&HistoricalAwards=false
• 关键词: SHINE; Faster; Boundary; Conforming; Simulations

Faster and more accurate predictions of space weather require model development of solar conditions. This project develops a computational model for turbulent solar convection by advancing the Compressible High-Order Unstructured Spectral difference (CHORUS) code. This interdisciplinary project will support two graduate students including a female Ph.D. student as well as an undergraduate research assistant. The PI will collaborate with NOAA’s Space Weather Prediction Center as well as NCAR’s High Altitude Observatory for broader dissemination of CHORUS++ as open-source code. This project accelerates the computational efficiency of CHORUS code and improves its accuracy for studying solar convection with an unprecedented capability to capture its hierarchical and inhomogeneous nature, and further exploits the capabilities of CHORUS to shed new light on multi-scale solar convection, and by extension, the fundamental physics of turbulent thermal convection under the influence of density stratification and rotation. The excellent parallel efficiency of CHORUS allows it to achieve the high computational resolution necessary to capture the intensely turbulent nature of the Sun’s convection zone (SCZ). In this project, CHORUS will be improved in three aspects: 1) a boundary- conforming transfinite mapping will be designed to completely remove numerical errors induced by iso-parametric mapping; 2) the order of accuracy in space will be improved from third-order (p2 elements) to sixth-order (p5 elements); and 3) p-refinements and local time stepping capabilities will be equipped for higher resolution in both space and time. The resultant CHORUS++ code will be over 100 times faster than CHORUS. Turbulence in the solar atmosphere is driven by thermal convection which transports heat from the deep solar interior to the surface layers where it is radiated into space. Turbulent convection in turn establishes mean flows and hydrodynamic dynamo action that regulates solar variability. An essential factor in establishing inhomogeneity is the extreme variation in gas density of order 1 million across the convection zone, which produces a commensurate disparity in the dynamical length and time scales. Small thermal plumes driven by radiative cooling in the upper boundary layer merge into larger-scale coherent structures deeper down. This vast dynamical range poses formidable modeling challenges that push the limits of computational fluid dynamics that require local mesh refinements and local time stepping for parallel computations.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.

更快、更准确的空间天气预测需要太阳条件的模型开发，该项目通过推进可压缩高阶非结构化光谱差（CHORUS）代码来开发湍流太阳对流的计算模型。该跨学科项目将支持两名研究生，其中包括一名。该项目负责人将与 NOAA 的空间天气预报中心以及 NCAR 的高空天文台合作，以更广泛地传播该信息。 CHORUS++ 作为开源代码，这加速了 CHORUS 代码的计算效率，并提高了其研究太阳对流的准确性，并具有前所未有的能力来捕获其分层和不均匀性质，并进一步利用 CHORUS 的功能为多方面研究提供新的思路。 CHORUS 出色的并行效率使其能够实现捕获太阳对流所需的高计算分辨率。太阳对流区（SCZ）的强烈湍流性质在该项目中，CHORUS 将在三个方面进行改进：1）将设计边界一致的超限映射，以完全消除等参数映射引起的数值误差；空间精度的阶数将从三阶（p2 元素）提高到六阶（p5 元素），并且 3) 将配备 p 细化和本地时间步进功能，以实现更高的空间和分辨率；由此产生的 CHORUS++ 代码将比 CHORUS 快 100 倍。太阳大气中的湍流是由热对流驱动的，热对流将热量从太阳内部深处传输到表面层，然后再辐射到太空。调节太阳变化的流动和水动力发电机作用是建立不均匀性的一个重要因素是对流区气体密度的极端变化，其产生了 100 万数量级。由上边界层的辐射冷却驱动的小热羽流向下融合成更大规模的相干深层结构，这带来了巨大的建模挑战，突破了计算流体动力学的极限。局部网格细化和并行计算的局部时间步进。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Arbitrarily high-order accurate simulations of compressible rotationally constrained convection using a transfinite mapping on cubed-sphere grids

使用立方球网格上的超限映射对可压缩旋转约束对流进行任意高阶精确模拟

• DOI: 10.1063/5.0158146
• 发表时间: 2023-08
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: Chen, Kuangxu;Liang, Chunlei;Wan, Minping
• 通讯作者: Wan, Minping

Extending the Spectral Difference Method with Divergence Cleaning (SDDC) to the Hall MHD Equations

将具有发散清理 (SDDC) 的谱差法扩展到霍尔 MHD 方程

• DOI: 10.22191/nejcs/vol5/iss1/1
• 发表时间: 2023-06
• 期刊: Northeast Journal of Complex Systems
• 作者: Hankey, Russell J.;Chen, Kuangxu;Liang, Chunlei
• 通讯作者: Liang, Chunlei