NSF Award
2310372
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. <br/><br/>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.<br/><br/>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.
