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A small inclination is capable of driving self-organization of a fluid mixture much like cars on highway lanes!
The behaviour of a fluid mixture under thermal stress is rather intriguing. More than 150 years ago Charles Soret showed that thermal differences within mixtures induce separation. The resulting concentration difference adds a density mismatch to the thermal one giving rise to convection in many cases.
Convecting fluids organize themselves into different structures (in our case, square patterns) to optimize heat flux. If the fluid container is tilted no modification of the convective patterns was previously observed for angles smaller than 10 degrees.
In this study we show that marginal inclinations of about 1 degree have a great impact on the global re-arrangement of the fluid if enough time is left. The columns of vertical-moving fluid, in fact, slowly self-organize into parallel lanes moving in opposite directions, much like cars in opposite lanes of a super-highway.
This collective behaviour also recalls the results of simulations of pedestrians moving in opposite directions in a narrow street and can help shading light in large convective motions like that of oceanic masses of fluid related to thermo-haline convection.
The study was performed in collaboration with Prof Frank Scheffold and Prof Alberto Vailati.
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Milano - Physics Dept. (italian)
Milano - Physics Dept. (english)
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