The Uniturbulence and Alfvén Wave Solar Model (UAWSoM) in MPI-AMRVAC

¹ Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B Bus 2400, 3001 Leuven, Belgium
² Starion Group S.A., Rue des Etoiles 140, 6890 Libin, Belgium
³ Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, Ringlaan -3- Av. Circulaire, 1180 Brussels, Belgium

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 12 June 2025
Accepted: 30 October 2025

Abstract

Context. The coronal heating problem and the generation of the solar wind remain fundamental challenges in solar physics. While approaches based on, e.g., the Alfvén Wave Solar Model (AWSoM) have proven highly successful in reproducing the large-scale structure of the solar corona, they inherently neglect contributions from additional wave modes that arise when the effects of transverse structuring are fully incorporated into the magnetohydrodynamic (MHD) equations.

Aims. In this paper, we compare the respective roles of heating driven by kink waves and Alfvén waves in sustaining a region of the solar atmosphere. We employ newly developed physics and radiative cooling modules within MPI-AMRVAC.

Methods. We extended the existing MHD physics module in MPI-AMRVAC by incorporating additional Alfvén and kink wave energy contributions to the MHD equations. We examined their roles in heating the solar atmosphere and driving the solar wind. To validate our approach, we compared our numerical results from Python-based simulations with those obtained using the UAWSoM module in MPI-AMRVAC. Furthermore, we assessed the heating efficiency of kink waves relative to that of pure Alfvén waves through two parameter studies: (1) exploring how different Alfvén wave reflection rates impact the simulated atmosphere and (2) varying the relative magnitudes of Alfvén and kink wave energy injections. Finally, we present the results of a larger scale domain fully sustained by kink wave-driven heating.

Results. Our results show that kink wave-driven (UAWSoM) models can sustain a stable atmosphere without requiring any artificial background heating terms, unlike traditional Alfvén-only models. We attribute this to the increased heating rate associated with kink waves compared with Alfvén waves, given the same energy injection.

Conclusions. Kink waves have the capacity to sustain a model plasma with temperature and density values representative of coronal conditions, without the need to resort to ad hoc heating terms.