Axisymmetric convective states of pure and binary liquids enclosed in a vertical cylinder and boundary conditions’ influence thereupon

The high Rayleigh number (Ra) axisymmetric convection regimes of $Pr=1$ pure and (⁠$Le=0.1$⁠, $Ψ=−0.2$⁠) binary liquids are numerically investigated and compared. The fluids are enclosed in a vertical cylinder of aspect ratio $height∕radius=2$ and heated from below, with either no-slip or free-slip kinematic lateral boundary conditions. Branches of solutions and transitions between states that occur as Ra is varied up to $O(105)$ are given, along with a description of the encountered bifurcations. When a free-slip condition is imposed along the circumference of the cell, pure fluid and binary liquid stationary flows are found to become identical at high Ra, an often reported feature. When the lateral boundary condition is set to no-slip, the high Ra steady flows of pure and binary liquid, although very similar, undergo different bifurcations. This is related with a locally quasiquiescent region present in both cases, the stability of which controls the flow regime in the whole fluid layer. A branch of resulting oscillatory states thus does not appear in the bifurcation diagram of the binary liquid.