Thermal convection is the driving force that sets stars and planets into motion. In a non-rotating fluid, the basic form of convection is relatively simple: hot fluid rises and cold fluid falls. However, in many stars and planets, the rotation makes the pattern of convection less straightforward. Rapid rotation constrains the fluid velocity to be independent of the rotation axis, so motion has to occur in columns, the Proudman-Taylor constraint. This remarkable behaviour is seen in laboratory experiments, and has a strong effect on the large scale dynamics in the cores and atmospheres of planets. The banded structure of Jupiter and Saturn is one consequence of this effect. This project involves a combination of numerical solutions of the fundamental equations together with asymptotic methods that exploit the fast rotation. Because of its many applications, rotating convection is studied by astrophysicists, geophysicists and applied mathematicians in many different countries; there are also several groups running laboratory experiments, and their results are being compared with numerical and asymptotic solutions to deepen our understanding of this fundamental process.
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).