Unexpected thermo-elastic effects in liquid glycerol by mechanical deformation

TL;DR

This study reveals unexpected thermo-elastic effects in liquid glycerol under shear deformation, showing that shear energy can induce measurable temperature variations, suggesting shear wave propagation and solid-like behavior in liquids.

Contribution

It demonstrates the existence of shear wave propagation and thermo-elastic effects in liquids, challenging the traditional view of instantaneous shear energy dissipation.

Findings

Thermal variations of about ±0.04°C observed during shear deformation.

Thermal effects depend nearly linearly on deformation amplitude.

Evidence of shear wave propagation extending up to hundreds of microns.

Abstract

It is commonly accepted that shear waves do not propagate in a liquid medium. The shear wave energy is supposed to dissipate nearly instantaneously. This statement originates from the difficulty to access static shear stress in macroscopic liquids. In this paper, we take a different approach. We focus on the stability of the thermal equilibrium while the liquid (glycerol) is submitted to a sudden shear strain at sub-millimetre scale. A thermal response of the deformed liquid is unveiled. The liquid exhibits simultaneous and opposite bands of about +0.04 {\deg}C and -0.04 {\deg}C temperature variations. The sudden thermal changes exclude the possibility of heat transfer and highlight the ability of the liquid to store the shear energy in non-uniform thermodynamic states. The thermal effects depend nearly linearly on the amplitude of the deformation supporting the hypothesis of a shear wave propagation (elastic correlations) extending up to several hundreds microns. This new physical effect can be explained in terms of the underlying phonon physics of confined liquids, which unveils a hidden solid-like response with many similarities to glassy systems.