Transport in Accretion Discs (Astrophysical and Geophysical Fluid Dynamics)
The material surrounding a massive astrophysical body such as a forming star or a compact object (in an active galaxy or in a binary stellar system) tends to form a rotating disc. Understanding the rich and complex dynamics of accretion discs is central to modern astrophysics and calls for in-depth understanding of the physics and mathematics of rotating and conducting fluids. The transport properties in such systems are governed by MHD turbulence resulting from the unstable interaction of a weak magnetic field with a conducting fluid in differential rotation, i.e. from the commonly named magnetorotational instability (MRI). Many questions remain unanswered regarding the nonlinear evolution of these instabilities, in particular the mechanism behind their saturation, the efficiency of the transport that they can achieve, and the effects of the vertical stratification and the geometry. Projects would involve developing models that would be numerically investigated to get insight into some aspects of the dynamics of accretion discs in relation with MRIs.
keywords: applied mathematics, astrophysics, MHD turbulence, magnetorotational instability
Astrophysical and Geophysical Fluid Dynamics
The group in Leeds is one of the leading groups in the field of Astrophysical and Geophysical Fluid Dynamics, with international reputation in dynamo theory, astrophysical MHD and convection. The strength of the group is recognised by the award of several prizes and special fellowships. The group also holds one of the largest grants ever awarded to the University of Leeds. The nine permanent members of staff work with eighteen postdocs and postgraduate students.
The group is actively engaged in research in a wide-range of areas of astrophysical and geophysical fluid dynamics: from planetary dynamics (the geodynamo and planetary dynamos) through solar, stellar and galactic dynamics to highly compressible and relativistic dynamics on the largest scales. Magnetic fields are a strong theme, and the group is interested in how planets (like the Earth), stars (like the Sun), neutron stars, black holes and galaxies generate their magnetic fields through dynamo action. On the Sun, the well-known eleven-year sunspot cycle is a manifestation of the solar dynamo; indeed the solar magnetic field underlies all solar magnetic phenomena such as solar flares, coronal mass ejections and the solar wind. In the Earth, magnetic fields are generated by convection in the molten iron core, and it has recently become possible to solve the fundamental equations that govern the motion of fluids and the generation of magnetic fields, and successfully reproduce many of the observed features of the geomagnetic field. At the other end of the scale, magnetic fields are implicated in the formation of spectacular jets coming from neutron stars, black holes and galaxies. Without magnetic fields, the group has interests in waves and hydrodynamic instabilities in rotating stratified fluids, with applications to the Earth's atmosphere and ocean (and with application to other planets).
The project is eligible for School of Mathematics Doctoral Training Grant funding - please contact us for more information.