D. Jou

Universitat Autònoma de Barcelona, Departament de Fisica, Faculty Member

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David Jou

Universitat Autònoma de Barcelona

Rosa Velasco

Vito Antonio Cimmelli

Tommaso Ruggeri

Università di Bologna

Shivam sharma

Indian Institute of Technology Bombay

William A. Sirignano

University of California, Irvine

Naval Chauhan

Francisco Lomeli

UNAM Universidad Nacional Autónoma de México

Gui-Qiang G. Chen

University of Oxford

Sebastian Soriano Matos(PERÚ)

Universidad nacional de ingenieria

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Papers by D. Jou

On the convexity of a nonequilibrium entropy and shock waves

Physics Letters A

We consider the limits ofvalidity ofa simple version of extended irreversible thermodynamics as g... more

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Contribution of the normal component to the thermal resistance of turbulent liquid helium

Zeitschrift für angewandte Mathematik und Physik, 2015

ABSTRACT Previous results for the velocity profile of the normal component of helium II in counte... more ABSTRACT Previous results for the velocity profile of the normal component of helium II in counterflow are used to evaluate the viscous contribution to the effective thermal resistance. It turns out that such a contribution becomes considerably higher than the usual Landau estimate, because in the presence of vortices, the velocity profile is appreciably different from the Poiseuille parabolic profile. Thus, a marked increase in the contribution of the normal component to the thermal resistance with respect to the viscous Landau estimate does not necessarily imply that the normal component is turbulent. Furthermore, we examine the influence of a possible slip flow along the walls when the radius of the tube becomes comparable with the phonon mean free path; this implies a reduction of the thermal resistance with respect to that obtained for nonslip boundary conditions.

Thermodynamics of polymer solutions under flow: Phase separation and polymer degradation

Advances in Polymer Science, 1995

... The direct influence of the viscous pressure tensor and other fluxes, such as heat flux or di... more

Measuring nonequilibrium temperature of forced oscillators

Physical review. E, Statistical, nonlinear, and soft matter physics, 2003

The meaning of temperature in nonequilibrium thermodynamics is considered by using a forced harmo... more The meaning of temperature in nonequilibrium thermodynamics is considered by using a forced harmonic oscillator in a heat bath, where we have two effective temperatures for the position and the momentum, respectively. We propose a concrete model of a thermometer to testify the validity of these different temperatures from the operational point of view. It is found that the measured temperature depends on a specific form of interaction between the system and a thermometer, which means that the zeroth law of thermodynamics cannot be immediately extended to nonequilibrium cases.

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Foundations and applications of a mesoscopic thermodynamic theory of fast phenomena

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996

A mesoscopic thermodynamic theory of fast phenomena is proposed. In principle, such a description... more A mesoscopic thermodynamic theory of fast phenomena is proposed. In principle, such a description should include an infinite number of moments of the velocity distribution; in a frequencywave-number space the corresponding transport coeKcients would be expressed in terms of a continued fraction expansion. Our objective is to eliminate from the description a maximum number of fast variables. This is achieved by deriving an asymptotic expression of the continued fraction. This procedure allows for a considerable reduction of the number of relevant variables, which are generally identified as the classical variables, such as energy and velocity, complemented by their corresponding dissipative cruxes, namely, the heat and the momentum fluxes. Two applications are investigated: ultrasound propagation in dilute gases and heat transport in dielectric crystals at very low temperature, where the phenomena of second sound is observed. It is shown that for ultrasound propagation, the inhuence of the fast variables can be described by introducing so-called effective relaxation times. This results in better agreement with experiments than earlier theoretical models and casts a light on the foundation of mesoscopic formalisms, such as extended irreversible thermodynamics. Concerning heat conduction in dielectric crystals, it is seen that the present description includes the three different modes of transport observed experimentally, namely, ballistic phonons, second sound waves, and diffusion. Our approach is a generalization of the models proposed by Cattaneo [

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Temperature and measurement: comparison between two models of nonequilibrium radiation

Physica A: Statistical Mechanics and its Applications, 1999

We generalize a previous proposal of an experiment (J. Fort, D. Jou, J.E. Llebot, Physica A 248 (... more We generalize a previous proposal of an experiment (J. Fort, D. Jou, J.E. Llebot, Physica A 248 (1998) 97) that, on the basis of predicted corrections to the Planck spectral law, may allow to determine experimentally what quantity is measured by a thermometer in steady-state nonequilibrium systems composed of matter and radiation. We include the photon number ux as an additional constraint. According to the model presented, the di erences between the spectra predicted from two possible temperature deÿnitions are higher than previously thought. In contrast to some previous papers, our model does not consider a speciÿc matter content for the system.

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Entropy flux in non-equilibrium thermodynamics

Physica A: Statistical Mechanics and its Applications, 2004

An important problem in thermodynamics is the link between the entropy ux and the heat ux, for ph... more An important problem in thermodynamics is the link between the entropy ux and the heat ux, for phenomena far from equilibrium. As an illustration we consider here the case of a rigid heat conductor subject to heating. The expression of the entropy ux is determined by the expressions of the evolution equations of the basic variables. It is shown that the coe cient relating entropy and heat uxes di ers far from equilibrium from the inverse of the non-equilibrium temperature Â. The particular case in which these two quantities are identical is examined in detail. A simple but intuitive physical illustration of the results is proposed. A comparison with information theory is also made: it is shown that agreement with Boltzmann's distribution function requires the introduction of non-local terms.

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Extended Irreversible Thermodynamics: Non-equilibrium Equations of State

Extended Irreversible Thermodynamics, 2009

ABSTRACT In Chap. 2 , we postulated the existence of a generalised entropy which is compatible wi... more ABSTRACT In Chap. 2 , we postulated the existence of a generalised entropy which is compatible with some classes of evolution equations for the fluxes. Otherwise stated, our formalism aims to describe the class of processes which are compatible with the existence of a non-equilibrium entropy whose rate of production is non-negative. Once the expression of the entropy is known, there is no difficulty in deriving the corresponding equations of state, which are directly obtained as the first derivatives of the entropy with respect to the basic variables. A natural question concerns the physical meaning of these equations of state, which, of course, depend on the fluxes and therefore differ from their analogous local-equilibrium expressions. In classical thermodynamics, it is known that the derivative of the entropy with respect to the internal energy (by keeping fixed the volume and the composition of the system) is the reciprocal of the absolute temperature; the derivatives with respect to the volume and to the number of moles yield the equilibrium pressure and (with a minus sign) the chemical potentials respectively (divided by the absolute temperature). It may then be asked whether the derivatives of the generalised entropy introduced in extended irreversible thermodynamics (EIT) still allow an absolute temperature to be defined, as well as a non-equilibrium pressure and a non-equilibrium chemical potential. Another important problem is to determine whether the non-equilibrium temperature and pressure are measurable by a thermometer and a manometer. These are subtle and unsolved problems which have however received partial answers during the last years stimulated by recent developments in glasses, granular matter, flowing suspensions, nuclear collisions, nano-systems, molecular dynamics and computer simulations, or in the analysis of fluctuations. The objective of the present chapter is to better apprehend the physical meaning of the generalised entropy and to pay detailed attention to the nature of the corresponding equations of state.

Classical, Rational and Hamiltonian Formulations of Non-equilibrium Thermodynamics

Extended Irreversible Thermodynamics, 2009

Mesoscopic description of boundary effects in nanoscale heat transport

Nanoscale Systems: Mathematical Modeling, Theory and Applications, 2012

We review some of the most important phenomena due to the phonon-wall collisions in nonlocal heat... more We review some of the most important phenomena due to the phonon-wall collisions in nonlocal heat transport in nanosystems, and show how they may be described through certain slip boundary conditions in phonon hydrodynamics. Heat conduction in nanowires of different cross sections and in thin layers is analyzed, and the dependence of the thermal conductivity on the geometry, as well as on the roughness is pointed out. We also analyze the effects of the roughness of the surface of the pores on the thermal conductivity of porous silicon. Thermoelectric effects are considered as well.In memory of Professor Carlo Cercignani

Spectral energy distribution and generalized Wien's law for photons and cosmic string loops

Physica Scripta, 2014

Physical objects with energy u w (l) ∼ l −3w with l a characteristic length and w a numerical con... more Physical objects with energy u w (l) ∼ l −3w with l a characteristic length and w a numerical constant (−1 ≤ w ≤ 1), lead to an equation of state p = wρ, with p the pressure and ρ the energy density. Special objects with this property are, for instance, photons (u = hc/l, with l the wavelength) with w = 1/3, and some models of cosmic string loops (u = (c 4 /aG)l, with l the length of the loop and a a numerical constant), with w = −1/3, and maybe other kinds of objects as, for instance, hypothetical cosmic membranes with lateral size l and energy proportional to the area, i.e. to l 2 , for which w = −2/3, or the yet unknown constituents of dark energy, with w = −1. Here, we discuss the general features of the spectral energy distribution of these systems and the corresponding generalization of Wien's law, which has the form T l 3w mp = constant, being l mp the most probable size of the mentioned objects.

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A generalized Einstein relation for flux-limited diffusion

Physica A: Statistical Mechanics and its Applications, 1998

In the presence of strong external ÿelds the Einstein relation between di usion coe cient and fri... more In the presence of strong external ÿelds the Einstein relation between di usion coe cient and friction coe cient must be modiÿed, and it becomes dependent on the ÿelds. We study how this transport relation should be generalized far from equilibrium for some particular forms of phenomenological ux limiters, which have been used in recent literature.

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Statistical physics and fluctuations in ballistic non-equilibrium systems

Physica a-Statistical Mechanics and Its Applications, 2009

In nonequilibrium systems in the ballistic transport regime, every point of the system contains p... more In nonequilibrium systems in the ballistic transport regime, every point of the system contains particles arriving from different regions–each of them at different temperatures–and there are only few collisions, in such a way that equilibrium between the different populations will be reached very slowly. Here, we tentatively approach the local distribution function by a superposition of local-equilibrium distribution functions with different temperatures, corresponding to the different starting positions of the particles. In a second-order expansion, we find a distribution function which depends not only on the Hamiltonian H but also on H2, and we study the additional contribution to energy fluctuations.

Non-classical Diffusion and Electrical Conduction

Extended Irreversible Thermodynamics, 1996

Hyperbolic Heat Transport in Rigid Conductors

Extended Irreversible Thermodynamics, 2009

From Thermoelastic Solids to Rheological Materials

Extended Irreversible Thermodynamics, 2009

Non-classical Diffusion

Extended Irreversible Thermodynamics, 2001

Multicomponent Systems

Extended Irreversible Thermodynamics, 1993

Shear induced polymer migration: analysis of the evolution of concentration profiles

Polymer, 2000

In order to analyze the evolution of the concentration profile experimentally observed by MacDona... more In order to analyze the evolution of the concentration profile experimentally observed by MacDonald and Muller under shear-induced polymer migration in a rotating cone-and-plate device, we use a constitutive equation for the diffusion flux, where the gradient of a generalized non-equilibrium chemical potential appears instead of the concentration gradient. From this model of coupling between diffusion and viscous pressure, together with the mass balance equation, we derive some general features of the concentration profile, the temporal behavior of the polymer concentration near the apex of the cone and some relevant trends of the dynamical process of polymer migration.

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Non-equilibrium chemical potential and polymer extraction from a porous matrix

Polymer, 2005

The influence of a flow on the transfer of a polymer solution from a porous matrix to a flowing f... more The influence of a flow on the transfer of a polymer solution from a porous matrix to a flowing fluid is analysed. Since the flow modifies the free energy of the solution, through stretching and orientation of the macromolecules, the thermodynamic driving force for polymer transport is modified with respect to that of a quiescent fluid. The consequences of this

On the convexity of a nonequilibrium entropy and shock waves

Physics Letters A

We consider the limits ofvalidity ofa simple version of extended irreversible thermodynamics as g... more

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Contribution of the normal component to the thermal resistance of turbulent liquid helium

Zeitschrift für angewandte Mathematik und Physik, 2015