MHD Simulations in Solar Physics

Numerous physical processes in the sun's atmosphere and convection zone like the development of sun spots or the rise of flux tubes are not understood in a satisfactory manner. These typically non-stationary phenomena can be traced back to the interaction of hydrodynamic properties and magnetic fields in the underlying plasma. The fluid motion in this area of the sun can be modeled by the equations of magnetohydrodynamics (MHD) for a partially-ionizised plasma coupled with the radiation transport equation.

The aim of this joint project with the group of Prof. Schüssler at the Max-Planck-Institut für Aeronomie is the development, implementation, and validation of a locally-adaptive, exact-in-time and higher-order finite volume scheme on unstructured grids in three space dimensions. To handle the required high resolution a parallel version for a distributed-memory architecture is currently being implemented. The code will be coupled with an efficient solver for the radiation transport equation.

The dynamics of flux tubes is mainly driven by magnetohydrodynamic instabilities of Kelvin-Helmholtz and Rayleigh-Taylor type. The figure below shows the evolution of a pure magnetohydrodynamic Rayleigh-Taylor instability.

A step towards the ''realistic'' setting in solar physics is provided by the following sequence of pictures. They show the rise of a toy flux tube in a gravitationally balanced atmosphere.

Examples:

2D Rayleigh-Taylor Instability:

(Click to see a 720 kB animated GIF)

The Rise of a Magnetic Flux Tube:

(Click to see an animated GIF)

Related Publications: