Dynamo Theory (Astrophysical and Geophysical Fluid Dynamics)

Dynamo theory addresses the fundamental problem of astrophysical magnetic fields, namely obtaining an understanding of the mechanism by which magnetic fields in cosmic bodies are maintained by the motions of the electrically conducting plasma contained therein. We are currently engaged in research into the Sun's dynamo mechanism and that of similar stars and also into the dynamo process within accretion discs, which is of a rather different nature. Dynamo theory is a fascinating topic, both physically and mathematically, drawing on several aspects of classical fluid dynamics, MHD (particularly MHD turbulence) and dynamical systems theory. We have adopted a whole range of approaches to the problem, from the analytical through to the intensely computational, making use of the massively parallel computational facilities available.

keywords: applied mathematics, astrophysical fluid dynamics, MHD turbulence, nonlinear dynamics

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).