Influence of gravity on dynamics of absorbing binary mixture

Abstract

A small perturbation in the absorption process disrupts the equilibrium, leading to surface tension gradients and, subsequently, Marangoni flows. This study examines the comparative role of gravity in the evolution of convective flows in an absorbing binary mixture considering Earth, Mars, the Moon and zero gravity. In the initial stage, the flow is driven by capillary forces towards the center of the perturbation, with gravity playing a negligible role. Over time, in the presence of gravity, the coupling of surface tension- and buoyancy-driven contributions gives rise to the formation of a periodic spatial structure and the generation of oscillations in time, thereby sustaining a weak instability. In contrast, in the absence of gravity, neither periodic structures nor oscillations are observed, as the potential competition between the two sources is eliminated. Instead, the flow pattern resembles that commonly seen in evaporating binary mixtures, exhibiting the formation of a stable rim and Marangoni spreading phenomena. In the intermediate regimes, when the gravity decreases from the Earth value to zero, the periodic patterns weaken, and become progressively more complex, while retaining a regular structure and expanding in size.