MPI-AMRVAC 3.0: Updates to an open-source simulation framework

Abstract

Context. Computational astrophysics nowadays routinely combines grid-adaptive capabilities with modern shockcapturing, high resolution spatio-temporal integration schemes in challenging multidimensional hydrodynamic and magnetohydrodynamic (MHD) simulations. A large, and still growing, body of community software exists, and we provide an update on recent developments within the open-source MPI-AMRVAC code. Aims. Complete with online documentation, the MPI-AMRVAC 3.0 release includes several recently added equation sets and offers many options to explore and quantify the influence of implementation details. While showcasing this flexibility on a variety of hydrodynamic and MHD tests, we document new modules of direct interest for state-of-the-art solar applications. Methods. Test cases address how higher-order reconstruction strategies impact long-term simulations of shear layers, with and without gas-dust coupling effects, how runaway radiative losses can transit to intricate multi-temperature, multiphase dynamics, and how different flavors of spatio-temporal schemes and/or magnetic monopole control produce overall consistent MHD results in combination with adaptive meshes. We demonstrate the use of super-time-stepping strategies for specific parabolic terms and give details on all the implemented implicit-explicit integrators. A new magneto-frictional module can be used to compute force-free magnetic field configurations or for data-driven timedependent evolutions, while the regularized-Biot-Savart-law approach can insert flux ropes in 3D domains. Synthetic observations of 3D MHD simulations can now be rendered on the fly, or in post-processing, in many spectral wavebands. Results. A particle module as well as a generic field line tracing module, fully compatible with the hierarchical meshes, can be used to do anything from sampling information at prescribed locations, to following the dynamics of charged particles and realizing fully two-way coupled simulations between MHD setups and field-aligned nonthermal processes. We provide reproducible, fully demonstrated tests of all code functionalities. Conclusions. While highlighting the latest additions and various technical aspects (e.g., reading in datacubes for initial or boundary conditions), our open-source strategy welcomes any further code usage, contribution, or spin-off development.

Legolas 2.0: Improvements and extensions to an MHD spectroscopic framework

“…When assembling the matrices every matrix element undergoes a check whether their associated state vector components are present in the state vector (12). If an element does not appear it is skipped and never added to the matrix, and because the assembly process is dynamic there is no (re)allocation of the matrices needed.…”

“…For MHD, associated with the state vector (3), the matrices have dimensions 80 × 80 (i.e. 16N ); while for HD, associated with the state vector (12), the matrices have dimensions 50 × 50 (i.e. 10N ).…”

“…These codes usually rely on finite volume methods and block-based grid structures, allowing for massively parallelised solver capabilities across a large number of cores. Examples include MPI-AMRVAC, a modular, parallel adaptive mesh refinement (AMR) framework for solving hyperbolic partial differential equations [22,25,12]; FLASH, a highperformance AMR multi-physics application code [8]; PLUTO, targeting high-mach number flows in astrophysical fluid dynamics on AMR grids; Athena++, a general relativistic MHD code and AMR framework; ENZO, a community-driven AMR code tailored to multi-physics hydrodynamic astrophysical applications [3]; and the Black Hole Accretion Code BHAC, capable of solving the ideal general relativistic MHD equations in multiple dimensions on arbitrary stationary spacetimes using an efficient parallel block-based approach [21,20].…”

Rotational Flows in Solar Coronal Flux Rope Cavities

“…The numerical experiment is performed using the fully opensource, adaptive-grid, parallelized Adaptive Mesh Refinement Versatile Advection Code 1 (Porth et al 2014;Xia et al 2018;Keppens et al 2021Keppens et al , 2023. We use a Cartesian coordinate system with x-and y-axis denoting the horizontal and vertical direction, respectively.…”

“…The time integration is performed using the strong stability-preserving Runge-Kutta three-step third-order method (SSPRK3). In order to control ∇ • B, we use the parabolic diffusion method (Keppens et al 2003(Keppens et al , 2023. We also exploit the magnetic field splitting (Xia et al 2018), fixing the equilibrium magnetic field B 0 and separating the time-dependent perturbation B 1 .…”