Fabio Peluso

Bio: Fabio Peluso is an academic researcher. The author has contributed to research in topics: Isochoric process. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Isochoric specific heat in the Dual Model of Liquids and comparison with the Phonon theory of Liquid Thermodynamics

Abstract: We continue in this paper to illustrate the implications of the Dual Model of Liquids (DML) by deriving the expression for the isochoric specific heat as a function of the collective degrees of freedom available at a given temperature and comparing it with the analogous expression obtained in the Phonon Theory of Liquid Thermodynamics. The Dual Model of Liquids has been recently proposed as a model describing the dynamics of liquids at the mesoscopic level. Bringing together the early pictures of Brillouin and Frenkel and the recent experimental outcomes obtained by means of high energy scattering, liquids are considered in the DML as constituted by a population of wave packets, responsible for the propagation of elastic and thermal perturbations, and of dynamic aggregates of molecules, in continuous re-arrangement, diving in an ocean of amorphous, disordered liquid. The collective degrees of freedom contribute to the exchange of energy and momentum between the material particles and the lattice particles, which the liquids are supposed to be composed of in the DML.First, we show that the expression obtained for the specific heat in the DML is in line with the experimental results. Second, its comparison with that of the Phonon Theory of Liquid Thermodynamics allows getting interesting insights about the limiting values of the collective degrees of freedom and on that of the isobaric thermal expansion coefficient, two quantities that appear related to each other in this framework

Non-Equilibrium Thermodynamics

Abstract: In the preceding chapters with few exceptions we studied systems at equilibrium. This means that the systems do not change or evolve over time.

How Does Heat Propagate in Liquids?

Abstract: In this paper, we proceed to illustrate the consequences and implications of the Dual Model of Liquids (DML) by applying it to the heat propagation. Within the frame of the DML, propagation of thermal (elastic) energy in liquids is due to wave-packet propagation and to the wave-packets’ interaction with the material particles of the liquid, meant in the DML as aggregates of molecules swimming in an ocean of amorphous liquid. The liquid particles interact with the lattice particles, a population of elastic wave-packets, by means of an inertial force, exchanging energy and momentum with them. The hit particle relaxes at the end of the interaction, releasing the energy and momentum back to the system a step forward and a time lapse later, like in a tunnel effect. The tunnel effect and the duality of liquids are the new elements that suggest on a physical basis for the first time, using a hyperbolic equation to describe the propagation of energy associated to the dynamics of wave-packet interaction with liquid particles. Although quantitatively relevant only in the transient phase, the additional term characterizing the hyperbolic equation, usually named the “memory term”, is physically present also once the stationary state is attained; it is responsible for dissipation in liquids and provides a finite propagation velocity for wave-packet avalanches responsible in the DML for the heat conduction. The consequences of this physical interpretation of the “memory” term added to the Fourier law for the phononic contribution are discussed and compiled with numerical prediction for the value of the memory term and with the conclusions of other works on the same topic.

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

Abstract: Abstract We show that a confined viscous liquid emits a dynamic thermal response upon applying a low frequency (∼1 Hz) shear excitation. Hot and cold thermal waves are observed in situ at atmospheric pressure and room temperature, in a viscous liquid (polypropylene glycol) at various thicknesses ranging from 100 µm up to 340 µm, upon applying a mechanical oscillatory shear strain. The observed thermal effects, synchronous with the mechanical excitation, are inconsistent with a viscous behaviour. It indicates that mesoscopic liquids are able to (partly) convert mechanical shear energy in non-equilibrium thermodynamic states. This effect called thermo-elasticity 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 thermo-elastic waves increases linearly by increasing the shear strain amplitude up to a transition to a non-linear thermal behavior, similar to a transition from an elastic to plastic regime. The thermo-elastic effects do not give rise to any change in stress measurements and thus the dynamic thermal analysis provides unique information about dynamic liquid properties.