Mixed thermal conditions in convection: how do continents affect the mantle's circulation?

Natural convection is omnipresent on Earth. A basic and well-studied model for it is Rayleigh-Benard convection, the fluid flow in a layer heated from below and cooled from above. Most explorations of Rayleigh-Benard convection focus on spatially uniform, perfectly conducting thermal boundary conditions, but many important geophysical phenomena are characterized by boundary conditions which are a mixture of conducting and adiabatic materials. For example, the differences in thermal conductivity between continental and oceanic lithospheres are believed to play an important role in plate tectonics. To study this, Wang et al. (J. Fluid Mech., vol. 817, 2017, R1), measure the effect of mixed adiabatic-conducting boundary conditions on turbulent Rayleigh-Benard convection, finding experimental proof that even if the total heat transfer is primarily affected by the adiabatic fraction, the arrangement of adiabatic and conducting plates is crucial in determining the large-scale flow dynamics.