Cosmological AMR MHD with Enzo

TL;DR

This paper introduces MHDEnzo, an extension of the Enzo cosmological simulation code, incorporating ideal MHD with advanced numerical methods to accurately simulate magnetic fields in cosmological contexts.

Contribution

The paper presents MHDEnzo, which integrates high-order Godunov solvers, constrained transport, and divergence-free reconstruction into Enzo for improved MHD cosmological simulations.

Findings

Successful implementation of ideal MHD in Enzo.

Accurate maintenance of magnetic divergence to machine precision.

Validated with cosmological and non-cosmological test problems.

Abstract

In this work, we present MHDEnzo, the extension of the cosmological code Enzo to include the effects magnetic fields through the ideal MHD approximation. We use a higher order Godunov Riemann solver for the computation of interface fluxes. We use two constrained transport methods to compute the electric field from those interface fluxes, which simultaneously advances the induction equation and maintains the divergence of the magnetic field. A third order divergence free reconstruction technique is used to interpolate the magnetic fields in the block structured AMR framework already extant in Enzo. This reconstruction also preserves the divergence of the magnetic field to machine precision. We use operator splitting to include gravity and cosmological expansion. We then present a series of cosmological and non cosmological tests problems to demonstrate the quality of solution resulting from this combination of solvers.