Convection with a strong vertical magnetic field: boundary layer versus interior dynamics.*

Convection in the presence of vertical magnetic field is important for understanding the dynamics of planetary interiors and stars. We investigate quasi-static magnetoconvection with direct numerical simulations, with an emphasis on understanding the limit of strong magnetic field in which the flows are anisotropic. The dynamics in the interior are distinguished from those observed in the boundary layer and the different force balances are presented through the lens of asymptotic theory that is verified with the simulations. We show that the scaling behavior within the boundary layers is critical for understanding the dynamics. In particular, our findings suggest that this system will not exhibit a heat transport scaling law that is independent of viscosity as the magnetic field strength is increased.