Evaluations of Numerical Flux Schemes of a Coronal MHD Model

Space weather forecasting requires precise estimation of the arrival time of eruptive events, which typically propagate through and interact with the solar atmosphere and solar wind. Therefore, the arrival time estimation depends on the accuracy of modelling the solar atmosphere and the complex interactions. For instance, the EUHFORIA 2.0 project expects an accurate and efficient coronal model that covers the region from the surface of the Sun up to 0.1AU, serving as the inner boundary condition for the heliospheric model.

Based on the open-source code COOLFluiD, we have developed a fully implicit MHD coronal model. The model has been validated by data-driven coronal simulations, and the fully implicit temporal solution significantly accelerates the numerical simulations. More physical mechanisms, e.g., the heating term(s), and numerical techniques, e.g., high-order schemes, are being developed to improve this model further. In this work, we specifically focus on the numerical flux schemes (Lax-Friedrichs, HLL, etc.) of the finite-volume MHD solver used by the coronal model, and evaluate their performance and impact on the coronal simulations. Both the internal structures and the quantities at the outer boundary are quantitatively compared.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 870405 (EUHFORIA 2.0).