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dc.contributor.authorGoldstraw, E. E.
dc.contributor.authorHood, A. W.
dc.contributor.authorBrowning, P. K.
dc.contributor.authorCargill, P. J.
dc.date.accessioned2018-01-05T13:30:09Z
dc.date.available2018-01-05T13:30:09Z
dc.date.issued2018-02-26
dc.identifier.citationGoldstraw , E E , Hood , A W , Browning , P K & Cargill , P J 2018 , ' Comparison of methods for modelling coronal magnetic fields ' , Astronomy & Astrophysics , vol. 610 , A48 . https://doi.org/10.1051/0004-6361/201731069en
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 251832188
dc.identifier.otherPURE UUID: 1af9c8c0-6206-4c69-903d-01d0ab0cb7f1
dc.identifier.otherBibCode: 2017arXiv171107458G
dc.identifier.otherScopus: 85042680541
dc.identifier.otherWOS: 000426130200002
dc.identifier.otherORCID: /0000-0003-2620-2068/work/58055173
dc.identifier.urihttp://hdl.handle.net/10023/12438
dc.descriptionFunding: STFC through the Consolidated grant ST/N000609/1 (AWH); STFC studentship, ST/I505999/1 (EEG).en
dc.description.abstractAims. Four different approximate approaches used to model the stressing of coronal magnetic fields due to an imposed photospheric motion are compared with each other and the results from a full time-dependent magnetohydrodynamic (MHD) code. The assumptions used for each of the approximate methods are tested by considering large photospheric footpoint displacements. Methods. We consider a simple model problem, comparing the full nonlinear magnetohydrodynamic evolution, determined with the Lare2D numerical code, with four approximate approaches. Two of these,magneto-frictional relaxation and a quasi-1D Grad-Shafranov approach, assume sequences of equilibria, whilst the other two methods, a second-order linearisation of the MHD equations and Reduced MHD, are time-dependent. Results. The relaxation method is very accurate compared to full MHD for force-free equilibria for all footpoint displacements but has significant errors when the plasma β0 is of order unity. The 1D approach gives an extremely accurate description of the equilibria away from the photospheric boundary layers, and agrees well with Lare2D for all parameter values tested. The linearised MHD equations correctly predict the existence of photospheric boundary layers that are present in the full MHD results. As soon as the footpoint displacement becomes a significant fraction of the loop length, the RMHD method fails to model the sequences of equilibria correctly. The full numerical solution is interesting in its own right, and care must be taken for low β0 plasmas if the viscosity is too high.
dc.format.extent15
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysicsen
dc.rights© 2017, ESO. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1051/0004-6361/201731069en
dc.subjectSun: coronaen
dc.subjectSun: magnetic fieldsen
dc.subjectMagnetohydrodynamics (MHD)en
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subject3rd-NDASen
dc.subject.lccQBen
dc.subject.lccQCen
dc.titleComparison of methods for modelling coronal magnetic fieldsen
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews.Applied Mathematicsen
dc.contributor.institutionUniversity of St Andrews.School of Mathematics and Statisticsen
dc.identifier.doihttps://doi.org/10.1051/0004-6361/201731069
dc.description.statusPeer revieweden
dc.identifier.urlhttp://adsabs.harvard.edu/abs/2017arXiv171107458Gen


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