Gary develops global three-dimensional time-dependent computer models to study the structure and dynamics of the interiors of planets and stars. The first in this series of models was written in the 1980s to study the solar dynamo. A modified version of this model was used for pre-flight studies and post-flight analyses of a rotating fluid dynamics experiment flown aboard NASA Space Shuttles in 1985 and 1995. In his studies of geodynamics he has simulated global circulation and convection in the Earth's atmosphere, mantle and core. He has also simulated convection and magnetic field generation in the deep interiors of giant gas planets like Jupiter and Saturn.

Gary and colleagues, Paul Roberts (UCLA) and Rob Coe (UCSC), study the internal magnetohydrodynamics of the Earth's core, i.e., the geodynamo. This is the mechanism in the Earth's fluid outer core that maintains the geomagnetic field. Their computer simulations span millions of years, using an average numerical time step of 15 days. At the surface of the model Earth, the simulated magnetic field has an intensity, an axial dipole dominated structure, and a westward drift of the non-dipolar structure that are all similar to the Earth's. The model's solid inner core rotates slightly faster than the surface of the model Earth; this computer modeling result in 1995 served as a prediction for the Earth that several seismic analyses now support. Several spontaneous reversals of the magnetic dipole polarity also occur in the simulations, similar to those seen in the Earth's paleomagnetic record.

Gary and his former graduate student Tami Rogers (now at the University of Newcastle upon Tyne, UK) studied the internal magnetohydrodynamics of the sun using her spectral computer codes. Their simulations illustrate how gravity waves in the sun's deep radiative interior may be excited by turbulence in the outer convection zone.

Gary and his former graduate student Martha Evonuk studied the internal magnetohydrodynamics of giant planets using her finite volume codes. A recent dynamo simulation of the deep interior dynamics of a giant planet maintains a latitudinally banded surface zonal wind profile similar to those seen on the surfaces of Jupiter and Saturn. The simulation also displays banded patterns of the resulting magnetic field and gravity field at the surface, which serve as predictions for the Juno and Cassini observations at Jupiter and Saturn, respectively.

Gary and his former graduate student Darcy Ogden studied the supersonic multiphase dynamics of explosive volcanic eruptions using a library of computer codes, CFDLib, from the Los Alamos National Laboratory. When a standing shock wave (Mach disk) forms above the vent their simulations predict a flow profile within the erupting column that is very different than that which has been assumed in simple parameterized models.

Gary, Francis Nimmo and their former graduate student Erinna Chen studied circulations and induced magnetic fields in the subsurface oceans of Europa and Titan driven by tidal potentials using 3D MHD simulations.

Gary, Nic Brummell and their former graduate student Katelyn White studied magnetic field generation in laboratory dynamo experiments using 3D dynamo simulations.

Introduction to Modeling Convection in Planets and Stars

Publications