Thermal Shear Waves in Mesoscopic Liquids
Résumé
A thermal response is identified upon applying oscillatory shear excitation in the conventional viscous regime (frequency range within 0.08 to 0.8 Hz) of ordinary liquid (polypropylene glycol) at room temperature. The liquid confined between surfaces with high energy to reinforce the wetting contact and of low thermal conductivity generate almost instantaneous and reversible (hot and cold) thermal waves upon applying the oscillatory shear strain. The amplitude of thermal waves that can reach + 0.04 °C and-0.04 °C in amplitude, depends on the scale in the same way as the liquid elasticity which is hardly accessible for a thickness scale of the order of a millimeter. The observed thermal effects indicate that mesoscopic liquids are able to convert (partly) mechanical shear energy in local thermodynamic states, therefore exhibit local thermoelastic waves. A transition from a linear, thermoelastic behavior, to a non-linear behavior, similar in strain behavior to an elastic to plastic regime is identified from low to very large deformation.
Domaines
Matière Molle [cond-mat.soft]
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