Finite volume simulations of dynamos in ellipsoidal planets

Abstract

So far, numerical simulations have mostly considered buoyancy as the driving mechanism of the dynamo process. However, also precession can drive a dynamo, as first suggested by Bullard in 1949. We investigate the properties of precession-driven dynamos in ellipsoidal planets by the use of a finite volume code. In planets, it is much more effective to drive a precessional flow by the pressure differences induced by the topography of the precessing body rather than by viscous coupling to the walls. Numerical simulations are the only method offering the possibility to investigate the influence of the topography since laboratory experiments normally are constrained by the predetermined geometry of the vessel. We discuss how ellipticity of the planets can be included in our simulations by the use of a non-orthogonal grid. Here, we will present some first results and conclude that laminar precession-driven flows can drive kinematic dynamos.