Investigating the influence of the source-sink terms in a two-fluid global coronal model

¹ Institute of Physics, University of Marii. Curie-Skłodowska Pl. Marii. Curie-Skłodowskiej 5 20-031 Lublin, Poland
² Particle Physics and Universe Sciences (PAPU), Department of Physics, University of Helsinki Helsinki, Finland
³ Shenzhen Key Laboratory of Numerical Prediction for Space Storm, Institute of Space Science and Applied Technology, Harbin Institute of Technology 51805 Shenzhen, People’s Republic of China
⁴ Centre for Mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven 3001 Leuven, Belgium

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Received: 22 September 2025
Accepted: 9 January 2026

Abstract

Context. Global multi-fluid coronal models are crucial to enhancing our comprehension and prediction of space weather. This study offers new insights into the impact of source and sink terms in a two-fluid model of the partially ionised solar atmosphere and their implications for the dynamics of the solar corona, in the context of space-weather forecasting.

Aims. This study aims to extend the two-fluid global coronal model by incorporating source and sink terms that represent empirical formulations of coronal heating and radiative and thermal conduction losses. The paper presents a fresh perspective by comparing model performance with and without these terms in a two-fluid (ion-neutral) plasma framework.

Methods. This work employed the newly developed multi-fluid global coronal model, COolfluid COronal uNstrUcTure Multi-Fluid (COCONUT-MF), based on the Computational Object-Oriented Libraries for Fluid Dynamics (COOLFluiD) code. This code solves the equations separately for charged particles (ions + electrons) and the neutral gas to describe the dynamics of a partially ionized plasma. The model in this paper accounted for chemical (ionization and recombination) and non-ideal (collisional) dynamics due to neutrals, as well as empirical heating terms, thermal conduction, and radiative losses, which were incorporated into the energy equation.

Results. The paper discusses two steady-state solutions: one for a solar-minimum case (August 1, 2008) and one for a solar-maximum case (March 9, 2016). We demonstrate the importance of accounting for source-sink terms in two-fluid models to accurately describe the dynamics of the lower corona.

Conclusions. The obtained results underscore the necessity of incorporating source-sink terms in the accurate modelling of the dynamics of the solar corona. Such terms lead to more structured temperature profiles and improved predictions for space weather.