Back reaction of magnetic field on rotating penetrative convection

The origin of the Earth's and planetary magnetic field is thought to arise from the convective flow of conducting liquid metal, particularly iron, in the deep interior of planetary systems through dynamo action. In numerical simulations, the nature of the resulting magnetic field depends on the imposition of buoyancy profiles that drive convection. Additional influence of imposed magnetic field on convective flows have been studied to understand the back reaction of dynamo action on fluid flow. In the present study, onset of  magnetoconvection is investigated to understand the physical effects in polar regions of the Earth's core where buoyancy forces exhibit a substantial component along the rotation axis. A simplified plane layer convection setup has been used to investigate the fundamental physical mechanisms. Various strengths of uniform magnetic fields in both horizontal and vertical directions have been incorporated. The novel aspect of the study is the incorporation of thermally stable layers with weak and strong stratification. Imposition of thermally stable stratification reduces the threshold of convective instability. It also restricts heat transport to unstable regions only. However, rapid rotation favors penetration of axial velocity into the thermally stable region, although critical thermal forcing for initiating convection also increases. The spectral characteristics of the flow is significantly modified due to the imposition of a stable stratified layer with background uniform magnetic field.