Our aim is to propose a theory which goes beyond the classical formulation of thermodynamics. This is achieved by enlarging the space of basic independent variables, through the introduction of non-equilibrium variables, such as the dissipative fluxes appearing in the balance equations. The next step is to find evolution equations for the dissipative fluxes. Whereas the evolution equations for the classical variables are given by the usual balance laws, no general criteria exist concerning the evolution equations of the dissipative fluxes, with the exception of the restrictions imposed on them by the second law of thermodynamics.

https://iopscience.iop.org/article/10.1088/0034-4885/51/8/002/pdf

Extended irreversible thermodynamics

For three-dimensional photonic crystals, made either by top-down microfabrication or by bottom-up self-assembly approaches, to comply with the stringent requirements of optical telecommunication applications, their degree of structural perfection and optical quality must meet an exceptionally high standard. Only with such superior quality photonic crystals can their unique optical properties be harnessed in optical devices and circuits constructed from micrometer-sized optical components. In this paper, we present a new strategy for making silica colloidal crystal films with a sufficiently high level of structural perfection and optical quality to make it competitive as a practical route to photonic crystal optical components. The attainment of this goal takes due cognizance of three key synergistic factors in the film formation process. The first recognizes the necessity to prepare high-quality silica spheres, which are highly monodisperse, with a polydispersity index significantly better than 2%, and the second recognizes that the population of spheres must be devoid of even the smallest fraction of substantially smaller or larger spheres or sphere doublets. The latter turns out to have a minimal effect on the polydispersity index, and yet a major detrimental effect on the overall structural order of the film. The third concerns the film-forming method itself, which necessitated the development of a novel process founded upon isothermal heating evaporation-induced self-assembly (IHEISA) of spheres on a planar substrate. This new method has several advantages over previously reported ones. It is able to deposit very high-quality silica colloidal crystal film rapidly over large areas, with a controlled thickness and without any restrictions on sphere sizes.

Colloidal crystal films: advances in universality and perfection.

REVIEW ARTICLE: Extended irreversible thermodynamics

▪ Abstract This review summarizes recent experimental studies of instabilities in free-surface flows driven by thermocapillarity. Two broad classes are considered, depending upon whether the imposed temperature gradient is perpendicular (Marangoni-convection instability) or parallel (thermocapillary-convection instability) to the free surface. Both steady and time-dependent instabilites are reviewed in experiments employing both large- and small-aspect-ratio geometries of various symmetries.

/pdf/experiments-on-thermocapillary-instabilities-4sdfjyw4qz.pdf

Experiments on thermocapillary instabilities

Hydrodynamic and hydromagnetic stability

The thermodynamic implications of the first deviations with respect to the classical hydrodynamic behavior in high-frequency, short-wavelength phenomena are examined. The constitutive equations arising from an extended irreversible-thermodynamic formalism taking into account spatial inhomogeneities in the space of state variables are compared with those used in generalized hydrodynamics. The so-called exponential model for the memory function of the transverse-velocity correlation function is derived under the assumptions of extended irreversible thermodynamics only. Furthermore, it is also shown how more complicated memory functions can be derived. The results are carefully analyzed and compared with some microscopic derivations.

/pdf/generalized-hydrodynamics-and-extended-irreversible-uf2s8w7ekt.pdf

Generalized hydrodynamics and extended irreversible thermodynamics

A non-local generalization of extended irreversible thermodynamics is developed. Both the entropy flux and the evolution equation of the heat flux are obtained as constitutive equations of the theory. The latter equation is used to described the fluctuations of the heat flux in the Onsager-Machlup formalism.

On a Ginzburg-Landau constitutive equation for the evolution and fluctuations of the heat flux

A new thermodynamic approach, based on extended irreversible thermodynamics, is proposed to describe viscoelastic materials. The state space is widened by including the stress tensor and the heat flux vector among the set of independent state variables. These extra variables are satisfying evolution equations taking the form of first order time differential equations. The present formalism encompasses the classical models of Maxwell, Kelvin-Voigt, Poynting-Thomson as well as the thermoelastic body and the Newtonian fluid. This is achieved without appealing to an artificial decomposition of the stress and strain tensors into elastic and inelastic parts.

On a new thermodynamic description of viscoelastic materials

The influence of the vessel shape, the vessel size and heating on convective patterns in the Benard-Marangoni (B-M) instability has been analysed These influences can be quantitatively studied by means of some theoretical tools, often used to describe melting in two dimensions Experimental results show that a hexagonal geometry minimizes the disorder in the hexagonal pattern of B-M convection This disorder is maximum when the aspect ratio is about 53 The disorder increases when the distance to the threshold increases Etude systematique de l'influence de l'ecart au seuil, de la forme et de la taille du recipient sur la structure de l'instabilite de Benard-Marangoni Etude quantitative de ces influences Les resultats experimentaux montrent que le desordre est minimum lorsque le recipient est de forme hexagonale et passe dans ce cas par un maximum lorsque le rapport d'aspect est d'environ 53

Structural disorder in Benard-Marangoni convection

The inclusion of dissipative fluxes in the set of independent thermodynamic variables leads, among other features, to a modification of the equations of state. Here, we introduce into the van der Waals equation the generalized pressure obtained in extended irreversible thermodynamics and analyze the influence of a shear stress or a heat flux on the critical point of a fluid.

/pdf/generalized-van-der-waals-equation-for-nonequilibrium-fluids-4wmiv1nols.pdf

C. Perez-Garcia

Papers

Generalized hydrodynamics and extended irreversible thermodynamics

On a Ginzburg-Landau constitutive equation for the evolution and fluctuations of the heat flux

On a new thermodynamic description of viscoelastic materials

Structural disorder in Benard-Marangoni convection

Generalized van der Waals equation for nonequilibrium fluids