Regular Article - Flowing Matter
Stabilized convection in a ternary mixture with two Soret coefficients of opposite sign
E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Universite de Pau et des Pays de l’Adour, Anglet, France
2 Centre National d’Études Spatiales (CNES), 2, Place Maurice Quentin, Paris, France
3 Department of Structure of Matter, Thermal Physics and Electronics, Faculty of Physics, University Complutense of Madrid, Madrid, Spain
4 Dipartimento di Fisica “A. Pontremoli”, Università degli Studi di Milano, Milan, Italy
Accepted: 27 April 2022
Published online: 28 May 2022
We performed ground-based experiments on the sample polystyrene–toluene–cyclohexane in order to complement the experimental activities in microgravity conditions related to the ESA projects DCMIX4 and Giant Fluctuations. After applying a stabilizing thermal gradient by heating from above a layer of the fluid mixture, we studied over many hours the density variations in the bidimensional horizontal field by means of a Shadowgraph optical setup. The resulting images evidence the appearance of convective instability after a diffusive time associated with the binary molecular solvent consisting of toluene and cyclohexane, confirming the negative sign of the Soret coefficient of this mixture. After a larger diffusive time related to mass diffusion of the polystyrene in the binary solvent, convection was suppressed by the increasing stabilizing density gradient originated by the Soret-induced concentration gradient of the polymer. This is compatible with a positive sign of the Soret coefficient of the polymer in the binary solvent.
© The Author(s) 2022
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