Implementation of thermal conduction energy transfer models in the Bifrost Solar atmosphere MHD code

Fuente: arXiv
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Autori principali: Cherry, George, Gudiksen, Boris, Szydlarski, Mikolaj
Natura: Preprint
Pubblicazione: 2024
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author Cherry, George
Gudiksen, Boris
Szydlarski, Mikolaj
author_facet Cherry, George
Gudiksen, Boris
Szydlarski, Mikolaj
contents Context: Thermal conductivity provides important contributions to the energy evolution of the upper solar atmosphere, behaving as a non-linear concentration-dependent diffusion equation. Recently, different methods have been offered as best-fit solutions to these problems in specific situations, but their effectiveness and limitations are rarely discussed. Aims. We rigorously test the different implementations of solving the conductivity flux, in the massively-parallel magnetohydrodynamics code, Bifrost, with the aim of specifying the best scenarios for the use of each method. Methods: We compare the differences and limitations of explicit versus implicit methods, and analyse the convergence of a hyperbolic approximation. Among the tests, we use a newly derived 1st-order self-similar approximation to compare the efficacy of each method analytically in a 1D pure-thermal test scenario. Results: We find that although the hyperbolic approximation proves the most accurate and the fastest to compute in long-running simulations, there is no optimal method to calculate the mid-term conductivity with both accuracy and efficiency. We also find that the solution of this approximation is sensitive to the initial conditions, and can lead to faster convergence if used correctly. Hyper-diffusivity is particularly useful in aiding the methods to perform optimally. Conclusions: We discuss recommendations for the use of each method within more complex simulations, whilst acknowledging the areas of opportunity for new methods to be developed.
format Preprint
id arxiv_https___arxiv_org_abs_2409_07074
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Implementation of thermal conduction energy transfer models in the Bifrost Solar atmosphere MHD code
Cherry, George
Gudiksen, Boris
Szydlarski, Mikolaj
Solar and Stellar Astrophysics
Instrumentation and Methods for Astrophysics
Mathematical Physics
Context: Thermal conductivity provides important contributions to the energy evolution of the upper solar atmosphere, behaving as a non-linear concentration-dependent diffusion equation. Recently, different methods have been offered as best-fit solutions to these problems in specific situations, but their effectiveness and limitations are rarely discussed. Aims. We rigorously test the different implementations of solving the conductivity flux, in the massively-parallel magnetohydrodynamics code, Bifrost, with the aim of specifying the best scenarios for the use of each method. Methods: We compare the differences and limitations of explicit versus implicit methods, and analyse the convergence of a hyperbolic approximation. Among the tests, we use a newly derived 1st-order self-similar approximation to compare the efficacy of each method analytically in a 1D pure-thermal test scenario. Results: We find that although the hyperbolic approximation proves the most accurate and the fastest to compute in long-running simulations, there is no optimal method to calculate the mid-term conductivity with both accuracy and efficiency. We also find that the solution of this approximation is sensitive to the initial conditions, and can lead to faster convergence if used correctly. Hyper-diffusivity is particularly useful in aiding the methods to perform optimally. Conclusions: We discuss recommendations for the use of each method within more complex simulations, whilst acknowledging the areas of opportunity for new methods to be developed.
title Implementation of thermal conduction energy transfer models in the Bifrost Solar atmosphere MHD code
topic Solar and Stellar Astrophysics
Instrumentation and Methods for Astrophysics
Mathematical Physics
url https://arxiv.org/abs/2409.07074