Numerical experiments on thermal convection of highly compressible fluids with variable viscosity and thermal conductivity: Implications for mantle convection of super-Earths

摘要

Highlights?Highly compressible thermal convection with increasing thermal conductivity with depth.?A basal layer of stable thermal stratification can be formed in super-Earth’s mantle.?Super-Earths without mobile surface plates may have stably stratified layer above CMB.AbstractWe conduct a series of numerical experiments of thermal convection of highly compressible fluids in a two-dimensional rectangular box, in order to study the mantle convection on super-Earths. The thermal conductivity and viscosity are assumed to exponentially depend on depth and temperature, respectively, while the variations in thermodynamic properties (thermal expansivity and reference density) with depth are taken to be relevant for the super-Earths with 10?times the Earth’s. From our experiments we identified a distinct regime of convecting flow patterns induced by the interplay between the adiabatic temperature change and the spatial variations in viscosity and thermal conductivity. That is, for the cases with strong temperature-depend