Generation of mean flows in geophysics and astrophysics (Astrophysical and Geophysical Fluid Dynamics)

In many systems of geophysical and astrophysical interest, such as planets, stars, galaxies and accretion disks, large-scale flows are generated by the interaction of turbulence at small and moderate scales. Examples include the atmospheric winds on the Earth and jets on Jupiter and Saturn as well as the differential rotation in the Sun and other stars. In many cases the mechanism for driving these flows remains unclear.

This project, based within the Astrophysical and Geophysical Fluid Dynamics Group at Leeds, will examine possible mechanisms for driving such flows and determine how interactions can lead to large-scale flow generation and how the large-scale flows themselves modify the turbulence that generates them.

The group is a leader in the field of Astrophysical and Geophysical Fluid Dynamics, with international reputation in dynamo theory, astrophysical MHD and convection. It's strength has been recognised by the award of several prizes and special fellowships and 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).

keywords: applied mathematics, fluid dynamics, turbulence