3D Solar Flare simulations: a hybrid MHD-beam approach

About the Project

This PhD project will start by exploring the current state-of-the-art hybrid magnetohydrodynamic (MHD) particle beam flare models of Ruan et al. (2020), and Druett et al. (2023, 2024). It will finish with the creation of a new state-of-the-art: the first 3D MHD-beam solar flare simulations. The models created will also calculate the outward flux and spectra of non-thermal particles ejected into the heliosphere, connecting the project to space weather. The duration is 42 months (3.5 years) and includes work packages designed to grow the student’s expertise in MHD, 3D fluid-dynamics simulations, and hybridised MHD-energetic particle modelling in a step-by-step manner, while producing valuable research output at each stage.

Firstly, many 1D simulations have investigated the impacts of beams of electrons in flares with different spectral indices, lower energy cutoffs and pitch angles (Canfield & Gayley 1987, Allred et al. 2005, 2015, 2020, Druett et al. 2017, 2018, Carlsson et al. 2023). This study has not been performed in multi-dimensional simulations due to a lack of available simulation software. Ruan et al. (2020) developed the first beam-MHD hybrid model capable of performing this experiment. The experiment of Druett et al. (2023) further developed the simulation scenario so that chromospheric evaporation directly results from the energetic electron beams, and Druett et al. (2024) presented the analysis tools to perform a detailed investigation of such a flow. Therefore, the stage is set for this investigation to occur in multiple dimensions. In the first part of their PhD the student will run and analyse 7 affordable (2.5D) experiments varying parameters of the energetic particle beams. This research also represents an implementation and analysis exercise on an existing experiment design. This will allow the student to familiarise themselves with the relevant Physics, literature, Fortran code, Python analysis tools, and simulation setup while providing a valuable scientific study.

The student will next extend the 2D MPI-AMRVAC simulation from Druett et al. (2023) in the orthogonal direction to form a 3D domain, and include periodic boundary conditions in this dimension to create an extended “flare arcade” setup. In this experiment, beam electrons will not be included in the simulations: A similar experiment was performed by Ruan et al. (2023) although we have an updated flare evolution, and no analysis of the lower atmospheric evolution was previously made. This study will perform that lower atmospheric analysis, building on the previously published results. The student will also introduce a varying resistivity in the third dimension, with maximum value in the central locations in the cross-section direction (the centre of the arcade). This will enable the student to study the reconnection that occurs as a function of distance in the third dimension, how reconnection propagates away from an initial instability, and how this process manifests at the flare footpoints. This part of the project will provide the student with the opportunity to develop analysis tools for 3D experiments that we will use in the final part of the PhD, and also provide us with both concrete evidence of the 3D experiment costs and an opportunity in which to develop analysis tools and visualisation routines for these flares.

Finally the student will take the intimately 2-dimensional beam energy transport implementation of Ruan et al. (2020) and convert it into a flexible format, suitable for 2D and 3D experiments. Then the student will implement this into a simulation analogous to the one mentioned above, and thus provide a state-of-the-art 3D flare experiment with beam electron energy transport included. This investigation can be adjusted based on ideas that the student has generated throughout the PhD. However a plausible approach has also already been outlined. Energy leaving the model via the top or bottom of the model will be stored as output for the analysis of space weather impacts. The student will analyse their fully developed 3D experiment and seek observational counterparts for the discovered simulation behaviours.

Funding Notes

This is a self-funded research project.

We require applicants to have either an undergraduate honours degree (2:1) or MSc (Merit or Distinction) in a relevant science or engineering subject from a reputable institution.

Full details of how to apply can be found at the following link:

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Applicants can apply for a Scholarship from the University of Sheffield but should note that competition for these Scholarships is highly competitive: View Website