The Effect of Noncondensables on the Buoyancy-Thermocapillary Convection in Confined and Volatile Fluids

Convection in confined layers of volatile liquids has been studied extensively under atmospheric conditions. Recent experimental results [1] have shown that removing most of the air from a sealed cavity significantly alters the flow structure and, in particular, suppresses transitions between the different convection patterns found at atmospheric conditions. Yet, at the same time, this has almost no effect on the flow speeds in the liquid layer. To understand these results, we have formulated and numerically implemented a detailed transport model that accounts for mass and heat transport in both phases as well as the phase change at the interface. Surprisingly, the numerical simulations show that noncondensables have a large effect on buoyancy-thermocapillary flow at concentrations even as low as 1%, i.e., much lower than those achieved in experiment.