An Entropy-stable Ideal EC-GLM-MHD Model for the Simulation of the Three-dimensional Ambient Solar Wind

Abstract

The main aim of the current work is to apply the Roe+Lax–Friedrichs (LF) hybrid entropy-stable scheme to the simulation of the three-dimensional ambient solar wind. The governing equations for the solar wind flow and magnetic field utilize the entropy-consistent nine-wave magnetic field divergence diminishing ideal magnetohydrodynamics (MHD) equations, which are symmetric and Galilean invariant with some nonconservative terms proportional to the divergence of magnetic field or the gradient of the Lagrange multiplier ψ. By using solenoidality-preserving and non-negativity-preserving reconstruction, the divergence error is further constrained, and the densities and pressures are reliably guaranteed. Moreover, the entropy is used as an auxiliary equation to completely avoid the appearance of negative pressure, which is independent of any numerical flux and can be retrofit into any MHD equations straightforwardly. All the properties referred to above make the newly developed scheme more handy and robust to cope with the high Mach number or low plasma β situations. After the experiments of the entropy consistency and the robustness of the proposed entropy-stable scheme through two simple tests, we carry out the simulation of the large-scale solar wind structures for Carrington Rotation 2183 (CR 2183) in a six-component grid system with the initial potential field obtained from the Helioseismic and Magnetic Imager magnetogram by retaining spherical harmonics of degree 50. The comparisons of the numerical results with the remote sensing observations and in situ data show that the new model has the capability to produce structured solar wind.

A Volumetric Study of Flux Transfer Events at the Dayside Magnetopause

“…Even though the energy equation is used everywhere in the domain, the pressure is computed from the entropy after AMR operations such as coarse-to-fine prolongations and restrictions (Mignone et al 2012). This procedure is one of the many techniques that can be used to ensure pressure positivity in simulations where the magnetic energy is the dominant contribution to the total energy density (Lyon et al 2004;Ridley et al 2010;Li et al 2021).…”