We are interested in understanding many geophysical and astrophysical fluid dynamics problems, with a particular emphasis on rotating convection and magnetic field generation as they apply to Earth’s liquid outer core, planets and stars. Geophysical and astrophysical fluid dynamics is a highly interdisciplinary field that involves several areas of classical physics such as continuum mechanics and electrodynamics, applied mathematics sub-disciplines such as perturbation theory and numerical methods, as well as computational physics. Most of the problems of interest are highly nonlinear (e.g. turbulence) and cannot be solved with analytical techniques; modern super-computing facilities are a necessary resource.
Convection:
Density heterogeneities within a fluid system give rise to buoyancy forces. For the case of denser fluid overlying less dense fluid, these buoyancy forces can lead to overturning fluid motions (i.e., convection). When the internal buoyancy forces are large, this leads to the generation of convective turbulence. Convective turbulence is a fundamental physical process that controls the long time thermal evolution of planets and stars. Understanding how these motions are influenced, and often times, controlled, by the rotation of the system is a primary research topic in our group.
Planetary and Stellar Dynamos:
Most of the planets in the Solar System, the Sun and other observable stars, possess large-scale magnetic fields. In the absence of an energy source, these fields would decay. Indeed, the Earth's magnetic field is known to have existed for approximately 4 billion years. It is believed that planetary and stellar magnetic fields are sustained via dynamo action, whereby the kinetic energy of a turbulent, electrically conducting fluid is converted into magnetic energy. In the case of the Earth, the convecting liquid iron outer core is the primary source of the geomagnetic field. The dynamics of such systems are described mathematically with the equations for conservation of mass, momentum and energy. Moreover, the electrodynamics are accurately described by the pre-Maxwell laws of Faraday, Ampere, and Ohm. We are currently investigating the physics of these complex, magnetohydrodynamical systems with the use of both simplified models, and direct numerical simulation of the complete set of governing equations.