Driving convection in a fluid layer by a temperature gradient or a heat current

Abstract

Bifurcation properties, stability behavior, dynamics, and the heat transfer of convection in a horizontal fluid layer that is driven away from thermal equilibrium by imposing a vertical temperature difference are compared with those resulting from imposing a heat current. Similarities and differences are elucidated. In particular various paradigmatic backwards bifurcating convection structures that occur, e.g., in binary fluid mixtures are determined numerically for the two different driving mechanisms. Conditions are given under which current driven convection is stable when temperature driven convection is unstable.

Convection driven by temperature and composition flux with the same diffusivity

“…The pulsations differ from the oscillations at marginal stability in double diffusion (Veronis 1964, Turner 1973 and with multiple boundary conditions, (Welander 1989, Tsitverblit 2007, which occur for Ra > 0 with stabilising salinity present and in some thermohaline laboratory experiments (te Raa 2001, Whitehead et al 2005. They are also unlike the binary fluid oscillations (Matura and Lücke 2006) that are travelling waves. These occur in experiments in a layer with zero lateral velocity imposed at the top and bottom and apparently are linked to the Soret effect.…”