Geophysical & astrophysical fluid dynamics
We are a team of researchers interested in exploring the fascinating fluid dynamics of stars and planets. In particular, our interest lies in the interaction of magnetic fields with electrically conducting fluids  a subject called magnetohydrodynamics.
Staff
Publications
2023
Gupta, P., MacTaggart, D., Simitev, R. D. (2023) Differential rotation in convecting spherical shells with nonuniform viscosity and entropy diffusivity Fluids, 8, (doi: 10.3390/fluids8110288)
MacTaggart, D., Valli, A. (2023) Relative magnetic helicity in multiply connected domains Journal of Physics A: Mathematical and Theoretical, 56, (doi: 10.1088/17518121/acfd6c)
Raphaldini, B., Dikpati, M., Norton, A. A., Teruya, A. S. W., McIntosh, S. W., Prior, C. B., MacTaggart, D. (2023) Deciphering presolarstorm features of September2017 storm from global and local dynamics Astrophysical Journal,
Teed, R. J., Dormy, E. (2023) Solenoidal force balances in numerical dynamos Journal of Fluid Mechanics, 964, (doi: 10.1017/jfm.2023.332)
Simitev, R. D., Al dawoud, A., Aziz, M. H.N., Myles, R., Smith, G. L. (2023) Phenomenological analysis of simple ion channel block in large populations of uncoupled cardiomyocytes Mathematical Medicine and Biology, 40, pp. 175198. (doi: 10.1093/imammb/dqad001)
Al Sariri, T., Simitev, R. D., Penta, R. (2023) Optimal heat transport induced by magnetic nanoparticle delivery in vascularised tumours Journal of Theoretical Biology, 561, (doi: 10.1016/j.jtbi.2022.111372)
Alielden, K., MacTaggart, D., Ming, Q., Prior, C., Raphaldini, B. (2023) ARTop: an opensource tool for measuring active region topology at the solar photosphere RAS Techniques and Instruments, 2, pp. 398407. (doi: 10.1093/rasti/rzad029)
2022
Gupta, P., Simitev, R.D., MacTaggart, D. (2022) A study of global magnetic helicity in selfconsistent spherical dynamos Geophysical and Astrophysical Fluid Dynamics, 116, pp. 521536. (doi: 10.1080/03091929.2022.2137878)
Lachaud, Q., Aziz, M. H. N., Burton, F. L., Macquaide, N., Myles, R. C., Simitev, R. D., Smith, G. L. (2022) Electrophysiological heterogeneity in large populations of rabbit ventricular cardiomyocytes Cardiovascular Research, 118, pp. 31123125. (doi: 10.1093/cvr/cvab375)
Aziz, M. H.N., Simitev, R. D. (2022) Estimation of parameters for an archetypal model of cardiomyocyte membrane potentials International Journal of Bioautomation, 26, pp. 255272. (doi: 10.7546/ijba.2022.26.3.000832)
Simitev, R. D., MacTaggart, D., Teed, R., Candelaresi, S. (2022) Introduction Geophysical and Astrophysical Fluid Dynamics, 116, pp. 235236. (doi: 10.1080/03091929.2022.2107377)
Quinn, J. J., Simitev, R. D. (2022) Flute and kink instabilities in a dynamically twisted flux tube with anisotropic plasma viscosity Monthly Notices of the Royal Astronomical Society, 512, pp. 49824992. (doi: 10.1093/mnras/stac704)
Raphaldini, B., Prior, C. B., Mactaggart, D. (2022) Magnetic winding as an indicator of flare activity in solar active regions Astrophysical Journal, 927, (doi: 10.3847/15384357/ac4df9)
Mactaggart, D. (2022) Magnetic winding: theory and applications AGU Books, Wiley
Huethorst, E., Mortensen, P., Simitev, R. D., Gao, H., Pohjolainen, L., Talman, V., Ruskoaho, H., Burton, F. L., Gadegaard, N., Smith, G. L. (2022) Conventional rigid 2D substrates cause complex contractile signals in monolayers of human induced pluripotent stem cell derived cardiomyocytes Journal of Physiology, 600, pp. 483507. (doi: 10.1113/JP282228)
Faraco, D., Lindberg, S., MacTaggart, D., Valli, A. (2022) On the proof of Taylor’s conjecture in multiply connected domains Applied Mathematics Letters, 124, (doi: 10.1016/j.aml.2021.107654)
2021
Candelaresi, S., Hornig, G., MacTaggart, D., Simitev, R. D. (2021) On self and mutual winding helicity Communications in Nonlinear Science and Numerical Simulation, 103, (doi: 10.1016/j.cnsns.2021.106015)
Riello, M., Purgato, M., Bove, C., Tedeschi, F., MacTaggart, D., Barbui, C., Rusconi, E. (2021) Effectiveness of selfhelp plus (SH+) in reducing anxiety and posttraumatic symptomatology among care home workers during the COVID19 pandemic: a randomized controlled trial Royal Society Open Science, 8, (doi: 10.1098/rsos.210219)
MacTaggart, D., Prior, C., Raphaldini, B., Romano, P., Guglielmino, S.L. (2021) Direct evidence that twisted flux tube emergence creates solar active regions Nature Communications, 12, (doi: 10.1038/s41467021269817)
Teed, R. J., Latter, H. N. (2021) Axisymmetric simulations of the convective overstability in protoplanetary discs Monthly Notices of the Royal Astronomical Society, 507, pp. 55235541. (doi: 10.1093/mnras/stab2311)
Quinn, J., MacTaggart, D., Simitev, R. D. (2021) KelvinHelmholtz instability and collapse of a twisted magnetic nullpoint with anisotropic viscosity Astronomy and Astrophysics, 650, (doi: 10.1051/00046361/202140460)
Aziz, M. H.N., Simitev, R. D. (2021) Code for Estimation of Parameters for an Archetypal Model of Cardiomyocyte Membrane Potentials (doi: 10.5281/zenodo.4568662)
Mortensen, P., Gao, H., Smith, G., Simitev, R. D. (2021) Action potential propagation and block in a model of atrial tissue with myocytefibroblast coupling Mathematical Medicine and Biology, 38, pp. 106131. (doi: 10.1093/imammb/dqaa014)
Simitev, R. D., Busse, F. H. (2021) Onset of inertial magnetoconvection in rotating fluid spheres Fluids, 6, (doi: 10.3390/fluids6010041)
Mather, J. F., Simitev, R. D. (2021) Regimes of thermocompositional convection and related dynamos in rotating spherical shells Geophysical and Astrophysical Fluid Dynamics, 115, pp. 6184. (doi: 10.1080/03091929.2020.1762875)
Mortensen, P., Gao, H., Smith, G., Simitev, R. D. (2021) Addendum: Action potential propagation and block in a model of atrial tissue with myocytefibroblast coupling Mathematical Medicine and Biology, 38, pp. 292298. (doi: 10.1093/imammb/dqab005)
Da Silva Costa, A., Mortensen, P., HortigonVinagre, M. P., van der Heyden, M. A. G., Burton, F. L., Gao, H., Simitev, R. D., Smith, G. L. (2021) Electrophysiology of hiPSCcardiomyocytes cocultured with HEK cells expressing the inward rectifier channel International Journal of Molecular Sciences, 22, (doi: 10.3390/ijms22126621)
Mactaggart, D., Prior, C. (2021) Helicity and winding fluxes as indicators of twisted flux emergence Geophysical and Astrophysical Fluid Dynamics, 115, pp. 85124. (doi: 10.1080/03091929.2020.1740925)
MacTaggart, D., Prior, C. (2021) Magnetic winding – a key to unlocking topological complexity in flux emergence Journal of Physics: Conference Series, 1730, (doi: 10.1088/17426596/1730/1/012013)
2020
Silva, L., Gupta, P., Mactaggart, D., Simitev, R. (2020) Effects of shell thickness on crosshelicity generation in convectiondriven spherical dynamos Fluids, 5, (doi: 10.3390/fluids5040245)
Prior, C., Mactaggart, D. (2020) Magnetic winding: what is it and what is it good for? Proceedings of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences, 476, (doi: 10.1098/rspa.2020.0483)
Quinn, J., MacTaggart, D., Simitev, R. (2020) The effect of anisotropic viscosity on the nonlinear MHD kink instability Communications in Nonlinear Science and Numerical Simulation, 83, (doi: 10.1016/j.cnsns.2019.105131)
Riello, M., Purgato, M., Bove, C., Mactaggart, D., Rusconi, E. (2020) Prevalence of posttraumatic symptomatology and anxiety among residential nursing and care home workers following the first COVID19 outbreak in Northern Italy Royal Society Open Science, 7, (doi: 10.1098/rsos.200880)
2019
MacTaggart, D., Valli, A. (2019) Magnetic helicity in multiply connected domains Journal of Plasma Physics, 85, (doi: 10.1017/S0022377819000576)
Hori, K., Teed, R. J., Jones, C.A. (2019) Anelastic torsional oscillations in Jupiter's metallic hydrogen region Earth and Planetary Science Letters, 519, pp. 5060. (doi: 10.1016/j.epsl.2019.04.042)
MacTaggart, D., Fletcher, L. (2019) The plasmoid instability in a confined solar flare Monthly Notices of the Royal Astronomical Society, 486, pp. L96L100. (doi: 10.1093/mnrasl/slz068)
Prior, C., MacTaggart, D. (2019) Interpreting magnetic helicity flux in solar flux emergence Journal of Plasma Physics, 85, (doi: 10.1017/S0022377819000229)
Teed, R.J., Jones, C.A., Tobias, S.M. (2019) Torsional waves driven by convection and jets in Earth’s liquid core Geophysical Journal International, 216, pp. 123129. (doi: 10.1093/gji/ggy416)
Silva, L. A.C., Mather, J. F., Simitev, R. D. (2019) The onset of thermocompositional convection in rotating spherical shells Geophysical and Astrophysical Fluid Dynamics, 113, pp. 377404. (doi: 10.1080/03091929.2019.1640875)
MacTaggart, D. (2019) The tearing instability of resistive magnetohydrodynamics Springer
(2019) Topics in Magnetohydrodynamic Topology, Reconnection and Stability Theory 591, (doi: 10.1007/9783030163433)
2018
MacTaggart, D. (2018) The nonmodal onset of the tearing instability Journal of Plasma Physics, 84, (doi: 10.1017/S0022377818001009)
Silva, L. A.C., Simitev, R. D. (2018) Pseudospectral Code for Numerical Simulation of Nonlinear Thermocompositional Convection and Dynamos in Rotating Spherical Shells (doi: 10.5281/zenodo.1311203)
Silva, L. A.C., Simitev, R. D. (2018) Spectral Code for Linear Analysis of the Onset of Thermocompositional Convection in Rotating Spherical Fluid Shells (doi: 10.5281/zenodo.1307245)
Simitev, R. D., Busse, F. H. (2018) Flows and dynamos in a model of stellar radiative zones Journal of Plasma Physics, 84, (doi: 10.1017/S0022377818000612)
Hori, K., Teed, R.J., Jones, C.A. (2018) The dynamics of magnetic Rossby waves in spherical dynamo simulations: a signature of strongfield dynamos? Physics of the Earth and Planetary Interiors, 276, pp. 6885. (doi: 10.1016/j.pepi.2017.07.008)
Mortensen, P., Bin Noor Aziz, M. H., Gao, H., Simitev, R. D. (2018) Modelling and Simulations of Electrical Propagation in Transmural Slabs of Scarred Left Ventricular Tissue
2017
Teed, R., Hori, K., Tobias, S., Jones, C. A. (2017) Observation and Excitation of Magnetohydrodynamic Waves in Numerical Models of Earth's Core
Dacie, S., van DrielGesztelyi, L., Démoulin, P., Linton, M.G., Leake, J.E., MacTaggart, D., Cheung, M.C.M. (2017) Field distribution of magnetograms from simulations of active region formation Astronomy and Astrophysics, 606, (doi: 10.1051/00046361/201730767)
MacTaggart, D., Stewart, P. (2017) Optimal energy growth in current sheets Solar Physics, 292, (doi: 10.1007/s1120701711771)
MacTaggart, D., Vergori, L., Quinn, J. (2017) Braginskii magnetohydrodynamics for arbitrary magnetic topologies: coronal applications Journal of Fluid Mechanics, 826, pp. 615635. (doi: 10.1017/jfm.2017.463)
Teed, R. J., Proctor, M. R. E. (2017) Quasicyclic behaviour in nonlinear simulations of the shear dynamo Monthly Notices of the Royal Astronomical Society, 467, pp. 48584864. (doi: 10.1093/mnras/stx421)
Shumaylova, V., Teed, R. J., Proctor, M. R.E. (2017) Largeto smallscale dynamo in domains of large aspect ratio: kinematic regime Monthly Notices of the Royal Astronomical Society, 466, pp. 35133518. (doi: 10.1093/mnras/stw3379)
Labrosse, N., Bownes, J., Forrest, D., MacTaggart, D., McGookin, E., Poet, R., Ray, S., FischbacherSmith, M., Jackson, M., McEwan, M., Pringle Barnes, G., Sheridan, N. (2017) Preparing for the Journey: Supporting Students to Make Successful Transitions Into and Out of Taught Postgraduate Study
Simitev, R. D., Busse, F. H. (2017) Baroclinicallydriven flows and dynamo action in rotating spherical fluid shells Geophysical and Astrophysical Fluid Dynamics, 111, pp. 369379. (doi: 10.1080/03091929.2017.1361945)
Teed, R. (2017) Identifying MHD Waves in Numerical Models of the Geodynamo
Teed, R. (2017) Nonlinear Properties of the Shear Dynamo Model
Bownes, J., Labrosse, N., Forrest, D., Mactaggart, D., Senn, H., FischbacherSmith, M., Jackson, M., McEwan, M., Pringle Barnes, G., Sheridan, N., Biletskaya, T. (2017) Supporting students in the transition to postgraduate taught study in STEM subjects Journal of Perspectives in Applied Academic Practice, 5, pp. 311. (doi: 10.14297/jpaap.v5i2.280)
2016
MacTaggart, D., Guglielmino, S. L., Zuccarello, F. (2016) The prepenumbral magnetic canopy in the solar atmosphere Astrophysical Journal Letters, 831, (doi: 10.3847/20418205/831/1/L4)
Prior, C., MacTaggart, D. (2016) The emergence of braided magnetic fields Geophysical and Astrophysical Fluid Dynamics, 110, pp. 432457. (doi: 10.1080/03091929.2016.1216552)
Teed, R., Proctor, M. R.E. (2016) Destruction of largescale magnetic field in nonlinear simulations of the shear dynamo Monthly Notices of the Royal Astronomical Society, 458, pp. 28852889. (doi: 10.1093/mnras/stw490)
Matsui, H., Heien, E., Aubert, J., Aurnou, J. M., Avery, M., Brown, B., Buffett, B. A., Busse, F., Christensen, U. R., Davies, C. J., Featherstone, N., Gastine, T., Glatzmaier, G. A., Gubbins, D., Guermond, J.L., Hayashi, Y.Y., Hollerbach, R., Hwang, L. J., Jackson, A., Jones, C. A., Jiang, W., Kellogg, L. H., Kuang, W., Landeau, M., Marti, P. H., Olson, P., Ribeiro, A., Sasaki, Y., Schaeffer, N., Simitev, R. D., Sheyko, A., Silva, L., Stanley, S., Takahashi, F., Takehiro, S.i., Wicht, J., Willis, A. P. (2016) Performance benchmarks for a next generation numerical dynamo model Geochemistry, Geophysics, Geosystems, 17, pp. 15861607. (doi: 10.1002/2015GC006159)
MacTaggart, D., Gregory, S., Neukirch, T., Donati, J.F. (2016) Magnetohydrostatic modelling of stellar coronae Monthly Notices of the Royal Astronomical Society, 456, pp. 767774. (doi: 10.1093/mnras/stv2714)
Teed, R. (2016) Excitation of Torsional Waves in the Earth's Core
2015
Bezekci, B., Idris, I., Simitev, R.D., Biktashev, V.N. (2015) Semianalytical approach to criteria for ignition of excitation waves Physical Review E, 92, (doi: 10.1103/PhysRevE.92.042917)
Hori, K., Jones, C.A., Teed, R.J. (2015) Slow magnetic Rossby waves in the Earth's core Geophysical Research Letters, 42, pp. 66226629. (doi: 10.1002/2015GL064733)
Teed, R. J., Jones, C. A., Tobias, S. M. (2015) The transition to Earthlike torsional oscillations in magnetoconvection simulations Earth and Planetary Science Letters, 419, pp. 2231. (doi: 10.1016/j.epsl.2015.02.045)
MacTaggart, D., Guglielmino, S.L., Haynes, A.L., Simitev, R., Zuccarello, F. (2015) The magnetic structure of surges in smallscale emerging flux regions Astronomy and Astrophysics, 576, (doi: 10.1051/00046361/201424646)
Simitev, R. D., Kosovichev, A. G., Busse, F. H. (2015) Dynamo effects near transition from solar to antisolar differential rotation Astrophysical Journal, 810, (doi: 10.1088/0004637X/810/1/80)
Argungu, M., Bayram, S., Brook, B., Chakrabarti, B., Clayton, R. H., Daly, D. M., Dyson, R. J., Holloway, C., Manhas, V., Naire, S., Shearer, T., Simitev, R. D. (2015) Modelling Afferent Nerve Responses to Bladder Filling
Busse, F.H., Simitev, R.D. (2015) Planetary dynamos Elsevier B.V.
Teed, R., Jones, C., Tobias, S. (2015) Torsional Waves Operating in Geodynamo and Magnetoconvection Simulations
2014
Busse, F. H., Simitev, R. D. (2014) Quasigeostrophic approximation of anelastic convection Journal of Fluid Mechanics, 751, pp. 216227. (doi: 10.1017/jfm.2014.293)
Marti, P., Schaeffer, N., Hollerbach, R., Cebron, D., Nore, C., Luddens, F., Guermond, J.L., Aubert, J., Takehiro, S., Sasaki, Y., Hayashi, Y., Simitev, R., Busse, F.H., Vantieghem, S., Jackson, A. (2014) Full sphere hydrodynamic and dynamo benchmarks Geophysical Journal International, 197, pp. 119134. (doi: 10.1093/gji/ggt518)
Mactaggart, D., Haynes, A. L. (2014) On magnetic reconnection and flux rope topology in solar flux emergence Monthly Notices of the Royal Astronomical Society, 438, pp. 15001506. (doi: 10.1093/mnras/stt2285)
Jackson, A., Sheyko, A., Marti, P., Tilgner, A., C'ebron, D., Vantieghema, S., Simitev, R., Busse, F., Zhan, X., Schubert, G., Takehiro, S., Sasaki, Y., Hayashi, Y.Y., Ribeiro, A., Nore, C., Guermond, J.L. (2014) A spherical shell numerical dynamo benchmark with pseudo vacuum magnetic boundary conditions Geophysical Journal International, 196, pp. 712723. (doi: 10.1093/gji/ggt425)
Teed, R. J., Jones, C. A., Tobias, S. M. (2014) The dynamics and excitation of torsional waves in geodynamo simulations Geophysical Journal International, 196, pp. 724735. (doi: 10.1093/gji/ggt432)
Christie, M., Nandi, M., Borg, Y., Carapella, V., Mirams, G., Aston, P., Bayram, S., Simitev, R., Siggers, J., Chakrabarti, B. (2014) Mathematical Modelling of Heart Rate Changes in the Mouse
Teed, R., Jones, C., Tobias, S. (2014) Torsional Oscillations in Geodynamo and Magnetoconvection Simulations
Postgraduate research students
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Geophysical & Astrophysical Fluid Dynamics  Example Research Projects
Information about postgraduate research opportunities and how to apply can be found on the Postgraduate Research Study page. Below is a selection of projects that could be undertaken with our group.
Numerical simulations of planetary and stellar dynamos (PhD)
Supervisors: Radostin Simitev, Robert Teed
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
Using fluid dynamics and magnetohydrodynamics to model the magnetic fields of Earth, planets, the Sun and stars. Involves highperformance computing.
Observationallyconstrained 3D convective spherical models of the solar dynamo (Solar MHD) (PhD)
Supervisors: Radostin Simitev, David MacTaggart, Robert Teed
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
Solar magnetic fields are produced by a dynamo process in the Solar convection zone by turbulent motions acting against Ohmic dissipation. Solar magnetic activity affects nearEarth space environment and can harm modern technology and endanger human health. Further, Solar magnetism poses fundamental physical and mathematical problems, e.g. about the nature of plasma turbulence and the topology of magnetic field generation. Current models of the global Solar dynamo fall in two classes (a) meanfield dynamos (b) convectiondriven dynamos. The meanfield models are only phenomenological as they replace turbulent interactions by adhoc source and quenching terms. On the other hand, spherical convectiondriven dynamo models are derived from basic principles with minimal assumptions and potentially offer true predictive power; these can also be extended to other stars and giant planets. However, at present, convection driven dynamo models operate in a wrong dynamical regime and have limited success in reproducing a number of important 1 observations including (a) the sunspot cycle period, polarity reversals and the sunspot butterfly diagram, (b) the poleward migration of diffuse surface magnetic fields, (c) the polar field strength and phase relationships between poloidal/toroidal components. The aims of this project are to (a) develop a threedimensional convectiondriven Solar dynamo model constrained by assimilation of helioseismic data, and (b) start to use the model to estimate turbulent properties that determine the internal dynamics and activity cycles of the Sun.
Modelling the force balance in planetary dynamos (PhD)
Supervisors: Robert Teed, Radostin Simitev
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
Current simulations of magnetic field (the 'dynamo process') generation in planets are run, not under the conditions of planetary cores and atmospheres, but in a regime idealised for computations. To forecast changes in planetary magnetic fields such as reversals and dynamo collapse, it is vital to understand the actual fluid dynamics of these regions. The aim of this project is to produce simulations of planetary cores and atmospheres with realistic force balances and, in doing so, understand how such force balances arise and affect the dynamics of the flow. The importance of different forces (e.g. Coriolis, Lorentz, viscous forces) determine the dynamics, the dynamo regime, and hence the morphology and strength of the magnetic field that is produced. This project would involve working with existing numerical code to perform the simulations and developing new techniques to determine the heirarchy of forces at play.
Identifying waves in dynamo models (PhD)
Supervisors: Robert Teed
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
This project would involve using existing (and developing new) techniques to isolate and study magnetohydrodynamic (MHD) waves in numerical calculations. Various classes of waves exist and may play a role in the dynamo process (which generates planetary magnetic fields) and/or help us better understand changes in the magnetic field.
Magnetic helicity as the key to dynamo bistability (PhD)
Supervisors: David MacTaggart, Radostin Simitev
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
The planets in the solar system exhibit very different types of largescale magnetic field.The Earth has a strongly dipolar field, whereas the fields of other solar system planets, such as Uranus and Neptune, are far more irregular. Although the different physical compositions of the planets of the solar system will influence the behaviour of the largescale magnetic fields that they generate, the morphology of planetary magnetic fields can depend on properties of dynamos common to all planets. Here, we refer to an important and recent discovery from dynamo simulations. Remarkably, two very different types of chaotic dipolar dynamo solutions have been found to exist over identical values of the basic parameters of a generic model of convectiondriven dynamos in rotating spherical shells. The two solutions mentioned above can be characterised as ‘mean dynamos’, MD, where a strong poloidal field dominates and ‘fluctuating dynamos’, FD, where the poloidal component is weaker and the largescale field can be described as multipolar. Although these two states have been shown to be bistable (coexist) for a wide range of identical parameters, it is not clear how a particular state, MD or FD, is chosen and how/when one state can change to the other. Some of the bifurcations of such states has been investigated, but a deep understanding of the dynamics that cause the bifurcations remains to be developed. Since the magnetic topology of MD and FD states are fundamentally different, an important part of this project will be to probe the nature of MD and FD states by studying magnetic helicity, a magnetohydrodynamic invariant that combines information on the topology of the magnetic field with the magnetic flux. The role of magnetic helicity and other helicities (e.g. cross helicity) is currently not well understood in relation to MD and FD states, but these quantities are conjectured to be very important in the development of MD and FD states.
Bistability is also related to a very important phenomenon in dynamos  global field reversal. A strongly dipolar (MD) field can change to a transitional multipolar (FD) state before a reversal and then settle into another dipolar equilibrium (of opposite polarity) again after the reversal.This project aims to develop a coherent picture of how bistability operates in spherical dynamos. Since bistability is a fundamental property of dynamos, a characterisation of how bistable solutions form and develop is key for any deep understanding of planetary dynamos and, in particular, could be crucial for understanding magnetic field reversals.
Stellar atmospheres and their magnetic helicity fluxes (PhD)
Supervisors: Radostin Simitev, David MacTaggart, Robert Teed
Relevant research groups: Geophysical & Astrophysical Fluid Dynamics, Continuum Mechanics
Our Sun and many other stars have a strong largescale magnetic field with a characteristic time variation. We know that this field is being generated via a dynamo mechanism driven by the turbulent convective motions inside the stars. The magnetic helicity, a quantifier of the field’s topology, is and essential ingredient in this process. In turbulent environments it is responsible for the inverse cascade that leads to the largescale field, while the build up of its smallscale component can quench the dynamo.
In this project, the student will study the effects of magnetic helicity fluxes that happen below the stellar surface (photosphere), within the stellar atmosphere (chromosphere and corona) and between these two layers. This will be done using twodimensional mean field simulations that allow parameter studies for different physical parameters. A fully threedimensional model of a convective stellar wedge will then be used to provide a more detailed picture of the helicity fluxes and their effect on the dynamo. Using recent advancements that allow us to extract surface helicity fluxes from solar observations, the student will make use of observations to verify the simulation results. Other recent observational results on the stellar magnetic helicity will be used to benchmark the findings.
Seminars
Regular seminars relevant to the group are held as part of the Geophysical and Astrophysical Fluid Dynamics Seminar series. You can find a full list of the seminars within the school on the main seminars page, where you can subscribe to their respective calendars.
Former Staff
Professor David Fearn (retired)
Dr Luis Silva (industry)
Dr James F Mather (industry)
Dr Tom Elsden (lecturer, St Andrews)
Dr Simon Candelaresi (researcher, Stuttgart)
Our research involves a mixture of fundamental theory, mathematical modelling and high performance computing. We invite you to browse the staff pages for more insight into our specific research interests. For potential PhD students, please take a look at the possible projects on offer or contact a particular member of staff directly. To find out more about applying to the School officially, please see Postgraduate research opportunities.