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arXiv 2203.07043cond-mat.soft
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低频机械变形下介观液体中的热剪切波

Thermal Shear Waves induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation

Eni Kume, Laurence Noirez

摘要:

我们表明,两个低导热表面(Al2O3)之间的粘性液体发出的热响应施加低频(Hz)的剪切激发。在大气压和室温下,在施加机械振荡剪切应变时,在100微米至340微米范围内的各种厚度的聚丙二醇层中原位观察到热和冷热波。所观察到的热效应,同步的机械激励,是不一致的均匀粘性流。这表明介观液体在非平衡热力学状态下能够(部分)转换机械剪切能。在固体材料中,这种效应被称为热弹性。对机械剪切变形的热耦合的观察加强了弹性相关液体分子的假设。热弹性波的振幅通过增加剪切应变振幅线性地增加,直到过渡到非线性热行为,类似于弹性到塑性状态的应变行为。热弹性效应通过应力测量是不可检测的,因此表现为补充的液体动力学特性。

英文摘要:

We show that a viscous liquid confined between two low thermal conductive surfaces (Al2O3) emit a thermal response upon applying a low frequency (Hz) shear excitation. Hot and cold thermal waves are observed in situ at atmospheric pressure and room temperature, in polypropylene glycol layers of various thicknesses ranging from 100 microns up to 340 microns, upon applying a mechanical oscillatory shear strain. The observed thermal effects, synchronous with the mechanical excitation, are inconsistent with a homogeneous viscous flow. It indicates that mesoscopic liquids are able to (partly) convert mechanical shear energy in non-equilibrium thermodynamic states. This effect called thermoelasticity is well known in solid materials. The observation of a thermal coupling to the mechanical shear deformation reinforces the assumption of elastically correlated liquid molecules. The amplitude of the thermoelastic waves increases linearly by increasing the shear strain amplitude up to a transition to a non-linear thermal behavior, similar in strain behavior to an elastic to plastic regime. The thermo-elastic effects are not detectable via stress measurements and thus appear as a complementary liquid dynamic characterization.

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