Driving solar coronal MHD simulations on high-performance computers
arXiv:1908.08557 · doi:10.1080/03091929.2019.1643849
Abstract
The quality of today's research is often tightly limited to the available computing power and scalability of codes to many processors. For example, tackling the problem of heating the solar corona requires a most realistic description of the plasma dynamics and the magnetic field. Numerically solving such a magneto-hydrodynamical (MHD) description of a small active region (AR) on the Sun requires millions of computation hours on current high-performance computing (HPC) hardware. The aim of this work is to describe methods for an efficient parallelization of boundary conditions and data input/output (IO) strategies that allow for a better scaling towards thousands of processors (CPUs). The Pencil Code is tested before and after optimization to compare the performance and scalability of a coronal MHD model above an AR. We present a novel boundary condition for non-vertical magnetic fields in the photosphere, where we approach the realistic pressure increase below the photosphere. With that, magnetic flux bundles become narrower with depth and the flux density increases accordingly. The scalability is improved by more than one order of magnitude through the HPC-friendly boundary conditions and IO strategies. This work describes also the necessary nudging methods to drive the MHD model with observed magnetic fields from the Sun's photosphere. In addition, we present the upper and lower atmospheric boundary conditions (photospheric and towards the outer corona), including swamp layers to diminish perturbations before they reach the boundaries. Altogether, these methods enable more realistic 3D MHD simulations than previous models regarding the coronal heating problem above an AR -- simply because of the ability to use a large amount of CPUs efficiently in parallel.
arXiv comment26 pages, 12 figures, 1 table, accepted at GAFD
References in corpus (20)
- The Solar Optical Telescope for the Hinode Mission: An Overview
- On Solving the Coronal Heating Problem
- Heating of the Solar Chromosphere and Corona by Alfven Wave Turbulence
- An Ab Initio Approach to the Solar Coronal Heating Problem
- Extension of the MURaM radiative MHD code for coronal simulations
- Nonlinear Dynamics of the Parker Scenario for Coronal Heating
- Numerical sunspot models: Robustness of photospheric velocity and magnetic field structure
- Structure of solar coronal loops: from miniature to large-scale
- Coronal Heating, Weak MHD Turbulence and Scaling Laws
- On red shifs in the transition region and corona
- On the origin of the Type~{\sc ii} spicules - dynamic 3D MHD simulations
- Constant cross section of loops in the solar corona
- Observationally driven 3D MHD model of the solar corona above an active region
- A model for the formation of the active region corona driven by magnetic flux emergence
- Limitations of force-free magnetic field extrapolations: revisiting basic assumptions
- Plasma Beta Stratification in the Solar Atmosphere: A Possible Explanation for the Penumbra Formation
- Scaling laws of coronal loops compared to a 3D MHD model of an Active Region
- Coronal loops above an Active Region - observation versus model
- Coronal energy input and dissipation in a solar active region 3D MHD model
- Magnetic Helicity Reversal in the Corona at Small Plasma Beta