From ballistic to diffusive regimes in heat transport at nano-scales

in Comptes Rendus de l'Académie des Sciences. Série II, Mécanique, Physique, Chimie, Sciences de l'Univers, Sciences de la Terre (2011), 339

Extended Irreversible Thermodynamics

Book published by Springer (2010)

Variational principles for thermal transport in nanosystems with heat slip flow

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2010), 82

Second sound and shock waves in rigid crystals: an extended thermodynamic analysis

in Proceedings of CHT-08 ICHMT International Symposium on Advances in Computational Heat Transfer (2008)

A unified extended thermodynamic description of diffusion, thermo-diffusion, suspensions, and porous media

in Journal of Applied Mechanics-Transactions of the Asme (2006), 73(1), 16-20

It is shown that extended irreversible thermodynamics (EIT) provides a Unified description of a great variety of processes, including matter diffusion, thermo-diffusion, suspensions, and fluid flows in ... [more ▼]

It is shown that extended irreversible thermodynamics (EIT) provides a Unified description of a great variety of processes, including matter diffusion, thermo-diffusion, suspensions, and fluid flows in porous media. This is achieved by enlarging the set of classical variables, as mass, momentum and temperature by the corresponding fluxes of mass, momentum and heat. For simplicity, we consider only Newtonian fluids and restrict ourselves to a linear analysis: quadratic and higher order terms in the fluxes are neglected. In the case of diffusion in a binary mixture, the extra flux variable is the diffusion flux of one the constituents, say the solute. In thermo-diffusion, one adds the heat flux to the set of variables. The main result of the present approach is that the traditional equations of Fick, Fourier Soret, and Dufour are replaced by time-evolution equations for the matter and heat fluxes, such generalizations are useful in high-frequency processes. It is also shown that the analysis can be easily extended to the study of particle suspensions in fluids and to flows in porous media, when such systems can be viewed as binary mixtures with a solid and a fluid component. [less ▲]

Convection and interfacial mass exchange

in ESA Special Publication (2005, October 01)

Mass-exchange through fluid interfaces is ubiquitous in many natural and industrial processes. Yet even basic phase-change processes such as evaporation of a pure liquid are not fully understood, in ... [more ▼]

Mass-exchange through fluid interfaces is ubiquitous in many natural and industrial processes. Yet even basic phase-change processes such as evaporation of a pure liquid are not fully understood, in particular when coupled with fluid motions in the vicinity of the phase-change interface, or with microscopic physical phenomena in the vicinity of a triple line (where the interface meets a solid). Nowadays, many industries recognise that this lack of fundamental knowledge is hindering the optimisation of existing processes. Their modelling tools are too dependent on empirical correlations with a limited - and often unknown - range of applicability. In addition to the intrinsic multiscale nature of the phenomena involved in typical industrial processes linked to interfacial mass exchange, their study is highly multi-disciplinary, involving tools and techniques belonging to physical chemistry, chemical engineering, fluid dynamics, non-linear physics, non-equilibrium thermodynamics, chemistry and statistical physics. From the experimental point of view, microgravity offers a unique environment to obtain valuable data on phase-change processes, greatly reducing the influence of body forces and allowing the detailed and accurate study of interfacial dynamics. In turn, such improved understanding leads to optimisation of industrial processes and devices involving phase-change, both for space and ground applications. [less ▲]

Ballistic-diffusive heat conduction at nanoscale: GENERIC approach [rapid communication]

in Physics Letters A (2005), 339

Heat conduction in nanosize systems has to be studied in settings involving microscopic details that are not seen in the classical Fourier theory. G. Chen has suggested [Phys. Rev. Lett. 86 (2001) 2297] a ... [more ▼]

Heat conduction in nanosize systems has to be studied in settings involving microscopic details that are not seen in the classical Fourier theory. G. Chen has suggested [Phys. Rev. Lett. 86 (2001) 2297] a combination of the Cattaneo setting in which the velocity of the heat propagation is finite and the kinetic theory setting in which phonons are seen as heat carriers. In this Letter we show that if the Cattaneo and the kinetic theories are combined in a way that preserves the structure expressing their compatibility with thermodynamics (GENERIC structure) then both the Cattaneo and the kinetic equations become modified. The modified Cattaneo equations involve the term introduced by Chen and, in addition, new terms that are nonlinear in quantities that disappear at equilibrium. The kinetic equation is modified by new terms involving gradients of the heat flux and the local temperature. [less ▲]

An unified extended thermodynamic description of diffusion, thermodiffusion, suspensions and porous media

in Proceedings International Conference on thermal engineering theory and application, Beirut (Liban), 2004 (2004)

A comparative analysis of non-fickean thermodiffusion by EIT and GENERIC

in 1st international exergy, energy and environment symposium (2003)

Thermal instability of a rotating saturated porous medium heated from below and submitted to rotation

in European Physical Journal B -- Condensed Matter (2002), 29(4), 641-647

In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below. The effect of rotation is restricted to the Coriolis force, neglecting thus the ... [more ▼]

In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below. The effect of rotation is restricted to the Coriolis force, neglecting thus the centrifugal effects, the porous medium is described by Brinkman's model. The linear eigenvalue problem is solved by means of a modified Galerkin method. The behavior of the critical temperature gradient is discussed in terms of various parameters of the system for both stationary and overstable convections. Finally a weakly nonlinear analysis is provided to derive amplitude equations and to study the onset of Kuppers-Lortz instability. [less ▲]