# MAGNUS: A new resistive MHD code with heat flow terms

## TL;DR

This paper introduces MAGNUS, a new 3D resistive MHD simulation code incorporating heat transfer, validated through various tests, and capable of accurately modeling wave propagation and magnetic reconnection in the solar atmosphere.

## Contribution

The paper presents MAGNUS, a novel resistive MHD code with heat transfer, utilizing advanced numerical schemes and divergence control, specifically designed for solar atmospheric simulations.

## Key findings

- The code accurately preserves magnetic divergence within machine precision.
- Validated with 1D and 2D tests for ideal MHD, resistivity, and thermal conduction.
- Successfully simulated wave propagation and magnetic reconnection in solar conditions.

## Abstract

We present a new magnetohydrodynamic (MHD) code for the simulation of wave propagation in the solar atmosphere, under the effects of electrical resistivity, but not dominant, and heat transference in a uniform 3D grid. The code is based on the finite volume method combined with the HLLE and HLLC approximate Riemann solvers, which use different slope limiters like MINMOD, MC, and WENO5. In order to control the growth of the divergence of the magnetic field, due to numerical errors, we apply the Flux Constrained Transport method, which is described in detail to understand how the resistive terms are included in the algorithm. In our results, it is verified that this method preserves the divergence of the magnetic fields within the machine round-off error. For the validation of the accuracy and efficiency of the schemes implemented in the code, we present some numerical tests in 1D and 2D for the ideal MHD. Later, we show one test for the resistivity in a magnetic reconnection process and one for the thermal conduction, where the temperature is advected by the magnetic field lines. Moreover, we display two numerical problems associated with the MHD wave propagation. The first one corresponds to a 3D evolution of a vertical velocity pulse at the photosphere-transition-corona region, while the second one consists in a 2D simulation of a transverse velocity pulse in a coronal loop.