Wall mode transition and dynamics in quasistatic magnetoconvection*

In quasistatic magnetoconvection, subjected to a strong vertical magnetic field with no-slip sidewalls, the onset of convection is determined by a linear instability at the sidewalls leading to the so-called wall mode regime. However, later stages of the transition to turbulence past this primary instability are not currently well understood. In this talk, we present new 3D DNS results in an aspect ratio one box which track the development of the equilibrium solutions produced by this primary instability through a series of bifurcations leading to a variety of more dynamically complex invariant solutions, and further to states exhibiting chaotic dynamics. In particular, we will discuss how different transition mechanisms occur at different magnetic field strengths. At low magnetic field strengths, weakly chaotic solutions feature a coexistence between wall modes and a large-scale roll in the centre of the domain which persists to higher Rayleigh numbers (Ra), but at high magnetic field strengths, the large-scale roll exists only for a small range of Ra, and chaotic dynamics primarily arise due to the unsteady dynamics of the wall modes themselves.