München 2019 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 9: Poster

EP 9.7: Poster

Donnerstag, 21. März 2019, 16:30–19:00, Durchgangshalle

MHD simulation of rotating insulator planets' magnetospheres — •Justus Sagemüller and Joachim Saur — Institut für Geophysik und Meteorologie, Universität zu Köln

Magnetohydrodynamics is a useful approach to model the plasma dynamics around planetary bodies. This description needs to take into account that matter below the surface of rocky or gaseous planets is an insulator. This results in nontrivial boundary conditions because the simulations usually do not solve for the currents directly, but for the magnetic fields.

A solution to this problem has been given in Duling et al. 2014 with a poloidal-toroidal decomposition based on spherical-harmonic expansion. A direct implementation can work well in particular for e.g. Jovian moons, but has limited flexibility due to the need for a spherical-polar grid and large, pre-computed transformation matrices.

We generalise this scheme, aiming to make it applicable to rotating planets with strong, not axis-aligned intrinsic (dynamo) magnetic field -- the most extreme example being Neptune -- and implement it on a cartesian grid in the Athena++ code.

The essential rotation of the dynamo field is successfully tested for simple dipole examples, with the goal to ultimately apply the description for future models of Neptune's magnetosphere.