Higher modes of mixed buoyant-Marangoni unstable convection originated from a droplet dissolving in a liquid/liquid system with miscibility gap

Some phenomena, never observed before, concerning a system composed by two organic-liquid bi-component phases with a miscibility gap, used as transparent surrogates for immiscible metal alloys, are discussed and elucidated in the framework of experimental analyses and numerical simulations. It is shown that a single dissolving droplet at the bottom of a test cell behaves as an intriguing pattern-forming dynamical system leading to a wealth of different spatio-temporal modes of convection when the imposed temperature gradient is increased. The last part of the analysis is devoted to comparison with other similar phenomena (the flow instability pertaining to the Marangoni flow around bubbles surrounded by a liquid heated from above, and the case of rising buoyant jets), showing analogies and differences. Such a comparison is also used as a means to focus on the intrinsic nature of the present instability.