Nonequilibrium thermodynamics
{{#invoke:Sidebar collapsible  bodyclass = plainlist  titlestyle = paddingbottom:0.3em;borderbottom:1px solid #aaa;  title = Thermodynamics  imagestyle = display:block;margin:0.3em 0 0.4em;  image =  caption = The classical Carnot heat engine  listtitlestyle = background:#ddf;textalign:center;  expanded = Branches
 list1name = branches  list1title = Branches  list1 = Template:Startflatlist
 list2name = laws  list2title = Laws  list2 = Template:Startflatlist
 list3name = systems  list3title = Systems  list3 =
State 

Processes 
Cycles 
 list4name = sysprop  list4title = System properties
 list4 =
Functions of state 

Process functions 
 list5name = material  list5title = Material properties  list5 =
 list6name = equations  list6title = Equations  list6 = Template:Startflatlist
 Maxwell relations
 Onsager reciprocal relations
 Bridgman's equations
 Table of thermodynamic equations
 list7name = potentials  list7title = Potentials  list7 = Template:Startflatlist
 list8name = hist/cult  list8title = Template:Hlist  list8 =
History 

Philosophy 
Theories 

Key publications 
Timelines 
Template:Hlist 
 list9name = scientists  list9title = Scientists  list9 = Template:Startflatlist
 Bernoulli
 Carnot
 Clapeyron
 Clausius
 Carathéodory
 Duhem
 Gibbs
 von Helmholtz
 Joule
 Maxwell
 von Mayer
 Onsager
 Rankine
 Smeaton
 Stahl
 Thompson
 Thomson
 Waterston
 below = Book:Thermodynamics
}} Nonequilibrium thermodynamics is a branch of thermodynamics that deals with thermodynamic systems that are not in thermodynamic equilibrium. Most systems found in nature are not in thermodynamic equilibrium; for they are changing or can be triggered to change over time, and are continuously and discontinuously subject to flux of matter and energy to and from other systems and to chemical reactions. Nonequilibrium thermodynamics is concerned with transport processes and with the rates of chemical reactions.^{[1]} Many natural systems still today remain beyond the scope of currently known macroscopic thermodynamic methods.
The thermodynamic study of nonequilibrium systems requires more general concepts than are dealt with by equilibrium thermodynamics. One fundamental difference between equilibrium thermodynamics and nonequilibrium thermodynamics lies in the behaviour of inhomogeneous systems, which require for their study knowledge of rates of reaction which are not considered in equilibrium thermodynamics of homogeneous systems. This is discussed below. Another fundamental difference is the difficulty in defining entropy in macroscopic terms for systems not in thermodynamic equilibrium.^{[2]}^{[3]}
Contents
 1 Overview
 2 Basic concepts
 3 Stationary states, fluctuations, and stability
 4 Local thermodynamic equilibrium
 5 Entropy in evolving systems
 6 Flows and forces
 7 The Onsager relations
 8 Speculated thermodynamic extremum principles for energy dissipation and entropy production
 9 Applications of nonequilibrium thermodynamics
 10 See also
 11 References
 12 Further reading
 13 External links
Overview
Nonequilibrium thermodynamics is a work in progress, not an established edifice. This article will try to sketch some approaches to it and some concepts important for it.
Some concepts of particular importance for nonequilibrium thermodynamics include time rate of dissipation of energy (Rayleigh 1873,^{[4]} Onsager 1931,^{[5]} also^{[6]}^{[7]}), time rate of entropy production (Onsager 1931),^{[5]} thermodynamic fields,^{[8]}^{[9]}^{[10]} dissipative structure,^{[11]} and nonlinear dynamical structure.^{[7]}
Of interest is the thermodynamic study of nonequilibrium steady states, in which entropy production and some flows are nonzero, but there is no time variation.
One initial approach to nonequilibrium thermodynamics is sometimes called 'classical irreversible thermodynamics'.^{[3]} There are other approaches to nonequilibrium thermodynamics, for example extended irreversible thermodynamics,^{[3]}^{[12]} and generalized thermodynamics,^{[13]} but they are hardly touched on in the present article.
Quasiradiationless nonequilibrium thermodynamics of matter in laboratory conditions
According to Wildt^{[14]} (see also Essex^{[15]}^{[16]}^{[17]}), current versions of nonequilibrium thermodynamics ignore radiant heat; they can do so because they refer to laboratory quantities of matter under laboratory conditions with temperatures well below those of stars. At laboratory temperatures, in laboratory quantities of matter, thermal radiation is weak and can be practically nearly ignored. But, for example, atmospheric physics is concerned with large amounts of matter, occupying cubic kilometers, that, taken as a whole, are not within the range of laboratory quantities; then thermal radiation cannot be ignored.
Local equilibrium thermodynamics
The terms 'classical irreversible thermodynamics'^{[3]} and 'local equilibrium thermodynamics' are sometimes used to refer to a version of nonequilibrium thermodynamics that demands certain simplifying assumptions, as follows. The assumptions have the effect of making each very small volume element of the system effectively homogeneous, or wellmixed, or without an effective spatial structure, and without kinetic energy of bulk flow or of diffusive flux. Even within the thoughtframe of classical irreversible thermodynamics, care^{[7]} is needed in choosing the independent variables^{[18]} for systems. In some writings, it is assumed that the intensive variables of equilibrium thermodynamics are sufficient as the independent variables for the task (such variables are considered to have no 'memory', and do not show hysteresis); in particular, local flow intensive variables are not admitted as independent variables; local flows are considered as dependent on quasistatic local intensive variables. (In other writings, local flow variables are considered; these might be considered as classical by analogy with the timeinvariant longterm timeaverages of flows produced by endlessly repeated cyclic processes; examples with flows are in the thermoelectric phenomena known as the Seebeck and the Peltier effects, considered by Kelvin in the nineteenth century and by Onsager in the twentieth.^{[19]}^{[20]} These effects occur at metal junctions, which were originally effectively treated as twodimensional surfaces, with no spatial volume, and no spatial variation.) Also it is assumed that the local entropy density is the same function of the other local intensive variables as in equilibrium; this is called the local thermodynamic equilibrium assumption^{[6]}^{[7]}^{[11]}^{[12]}^{[19]}^{[21]}^{[22]}^{[23]} (see also Keizer (1987)^{[24]}). Radiation is ignored because it is transfer of energy between regions, which can be remote from one another. In the classical irreversible thermodynamic approach, there is allowed very small spatial variation, from very small volume element to adjacent very small volume element, but it is assumed that the global entropy of the system can be found by simple spatial integration of the local entropy density; this means that spatial structure cannot contribute as it properly should to the global entropy assessment for the system. This approach assumes spatial and temporal continuity and even differentiability of locally defined intensive variables such as temperature and internal energy density. All of these are very stringent demands. Consequently, this approach can deal with only a very limited range of phenomena. This approach is nevertheless valuable because it can deal well with some macroscopically observable phenomena.
Local equilibrium thermodynamics with materials with "memory"
A further extension of local equilibrium thermodynamics is to allow that materials may have "memory", so that their constitutive equations depend not only on present values but also on past values of local equilibrium variables. Thus time comes into the picture more deeply than for timedependent local equilibrium thermodynamics with memoryless materials, but fluxes are not independent variables of state.^{[25]}
Extended irreversible thermodynamics
Extended irreversible thermodynamics is a branch of nonequilibrium thermodynamics that goes outside the restriction to the local equilibrium hypothesis. The space of state variables is enlarged by including the fluxes of mass, momentum and energy and eventually higher order fluxes. The formalism is wellsuited for describing highfrequency processes and smalllength scales materials.
Basic concepts
There are many examples of stationary nonequilibrium systems, some very simple, like a system confined between two thermostats at different temperatures or the ordinary Couette flow, a fluid enclosed between two flat walls moving in opposite directions and defining nonequilibrium conditions at the walls. Laser action is also a nonequilibrium process, but it depends on departure from local thermodynamic equilibrium and is thus beyond the scope of classical irreversible thermodynamics; here a strong temperature difference is maintained between two molecular degrees of freedom (with molecular laser, vibrational and rotational molecular motion), the requirement for two component 'temperatures' in the one small region of space, precluding local thermodynamic equilibrium, which demands that only one temperature be needed. Damping of acoustic perturbations or shock waves are nonstationary nonequilibrium processes. Driven complex fluids, turbulent systems and glasses are other examples of nonequilibrium systems.
The mechanics of macroscopic systems depends on a number of extensive quantities. It should be stressed that all systems are permanently interacting with their surroundings, thereby causing unavoidable fluctuations of extensive quantities. Equilibrium conditions of thermodynamic systems are related to the maximum property of the entropy. If the only extensive quantity that is allowed to fluctuate is the internal energy, all the other ones being kept strictly constant, the temperature of the system is measurable and meaningful. The system's properties are then most conveniently described using the thermodynamic potential Helmholtz free energy (A = U  TS), a Legendre transformation of the energy. If, next to fluctuations of the energy, the macroscopic dimensions (volume) of the system are left fluctuating, we use the Gibbs free energy (G = U + PV  TS), where the system's properties are determined both by the temperature and by the pressure.
Nonequilibrium systems are much more complex and they may undergo fluctuations of more extensive quantities. The boundary conditions impose on them particular intensive variables, like temperature gradients or distorted collective motions (shear motions, vortices, etc.), often called thermodynamic forces. If free energies are very useful in equilibrium thermodynamics, it must be stressed that there is no general law defining stationary nonequilibrium properties of the energy as is the second law of thermodynamics for the entropy in equilibrium thermodynamics. That is why in such cases a more generalized Legendre transformation should be considered. This is the extended Massieu potential. By definition, the entropy (S) is a function of the collection of extensive quantities . Each extensive quantity has a conjugate intensive variable (a restricted definition of intensive variable is used here by comparison to the definition given in this link) so that:
We then define the extended Massieu function as follows:
where is Boltzmann's constant, whence
The independent variables are the intensities.
Intensities are global values, valid for the system as a whole. When boundaries impose to the system different local conditions, (e.g. temperature differences), there are intensive variables representing the average value and others representing gradients or higher moments. The latter are the thermodynamic forces driving fluxes of extensive properties through the system.
It may be shown that the Legendre transformation changes the maximum condition of the entropy (valid at equilibrium) in a minimum condition of the extended Massieu function for stationary states, no matter whether at equilibrium or not.
Stationary states, fluctuations, and stability
In thermodynamics one is often interested in a stationary state of a process, allowing that the stationary state include the occurrence of unpredictable and experimentally unreproducible fluctuations in the state of the system. The fluctuations are due to the system's internal subprocesses and to exchange of matter or energy with the system's surroundings that create the constraints that define the process.
If the stationary state of the process is stable, then the unreproducible fluctuations involve local transient decreases of entropy. The reproducible response of the system is then to increase the entropy back to its maximum by irreversible processes: the fluctuation cannot be reproduced with a significant level of probability. Fluctuations about stable stationary states are extremely small except near critical points (Kondepudi and Prigogine 1998, page 323).^{[26]} The stable stationary state has a local maximum of entropy and is locally the most reproducible state of the system. There are theorems about the irreversible dissipation of fluctuations. Here 'local' means local with respect to the abstract space of thermodynamic coordinates of state of the system.
If the stationary state is unstable, then any fluctuation will almost surely trigger the virtually explosive departure of the system from the unstable stationary state. This can be accompanied by increased export of entropy.
Local thermodynamic equilibrium
The scope of presentday nonequilibrium thermodynamics does not cover all physical processes. A condition for the validity of many studies in nonequilibrium thermodynamics of matter is that they deal with what is known as local thermodynamic equilibrium.
Local thermodynamic equilibrium of ponderable matter
Local thermodynamic equilibrium of matter^{[6]}^{[11]}^{[21]}^{[22]}^{[23]} (see also Keizer (1987)^{[24]} means that conceptually, for study and analysis, the system can be spatially and temporally divided into 'cells' or 'microphases' of small (infinitesimal) size, in which classical thermodynamical equilibrium conditions for matter are fulfilled to good approximation. These conditions are unfulfilled, for example, in very rarefied gases, in which molecular collisions are infrequent; and in the boundary layers of a star, where radiation is passing energy to space; and for interacting fermions at very low temperature, where dissipative processes become ineffective. When these 'cells' are defined, one admits that matter and energy may pass freely between contiguous 'cells', slowly enough to leave the 'cells' in their respective individual local thermodynamic equilibria with respect to intensive variables.
One can think here of two 'relaxation times' separated by order of magnitude.^{[27]} The longer relaxation time is of the order of magnitude of times taken for the macroscopic dynamical structure of the system to change. The shorter is of the order of magnitude of times taken for a single 'cell' to reach local thermodynamic equilibrium. If these two relaxation times are not well separated, then the classical nonequilibrium thermodynamical concept of local thermodynamic equilibrium loses its meaning^{[27]} and other approaches have to be proposed, see for instance Extended irreversible thermodynamics. For example, in the atmosphere, the speed of sound is much greater than the wind speed; this favours the idea of local thermodynamic equilibrium of matter for atmospheric heat transfer studies at altitudes below about 60 km where sound propagates, but not above 100 km, where, because of the paucity of intermolecular collisions, sound does not propagate.
Milne's 1928 definition of local thermodynamic equilibrium in terms of radiative equilibrium
Milne (1928),^{[28]} thinking about stars, gave a definition of 'local thermodynamic equilibrium' in terms of the thermal radiation of the matter in each small local 'cell'. He defined 'local thermodynamic equilibrium' in a 'cell' by requiring that it macroscopically absorb and spontaneously emit radiation as if it were in radiative equilibrium in a cavity at the temperature of the matter of the 'cell'. Then it strictly obeys Kirchhoff's law of equality of radiative emissivity and absorptivity, with a black body source function. The key to local thermodynamic equilibrium here is that the rate of collisions of ponderable matter particles such as molecules should far exceed the rates of creation and annihilation of photons.
Entropy in evolving systems
It is pointed out^{[29]}^{[30]}^{[31]}^{[32]} by W.T. Grandy Jr that entropy, though it may be defined for a nonequilibrium system, is when strictly considered, only a macroscopic quantity that refers to the whole system, and is not a dynamical variable and in general does not act as a local potential that describes local physical forces. Under special circumstances, however, one can metaphorically think as if the thermal variables behaved like local physical forces. The approximation that constitutes classical irreversible thermodynamics is built on this metaphoric thinking.
Flows and forces
The fundamental relation of classical equilibrium thermodynamics ^{[33]}
expresses the change in entropy of a system as a function of the intensive quantities temperature , pressure and chemical potential and of the differentials of the extensive quantities energy , volume and particle number .
Following Onsager (1931,I),^{[5]} let us extend our considerations to thermodynamically nonequilibrium systems. As a basis, we need locally defined versions of the extensive macroscopic quantities , and and of the intensive macroscopic quantities , and .
For classical nonequilibrium studies, we will consider some new locally defined intensive macroscopic variables. We can, under suitable conditions, derive these new variables by locally defining the gradients and flux densities of the basic locally defined macroscopic quantities.
Such locally defined gradients of intensive macroscopic variables are called 'thermodynamic forces'. They 'drive' flux densities, perhaps misleadingly often called 'fluxes', which are dual to the forces. These quantities are defined in the article on Onsager reciprocal relations.
Establishing the relation between such forces and flux densities is a problem in statistical mechanics. Flux densities () may be coupled. The article on Onsager reciprocal relations considers the stable nearsteady thermodynamically nonequilibrium regime, which has dynamics linear in the forces and flux densities.
In stationary conditions, such forces and associated flux densities are by definition time invariant, as also are the system's locally defined entropy and rate of entropy production. Notably, according to Ilya Prigogine and others, when an open system is in conditions that allow it to reach a stable stationary thermodynamically nonequilibrium state, it organizes itself so as to minimize total entropy production defined locally. This is considered further below.
One wants to take the analysis to the further stage of describing the behaviour of surface and volume integrals of nonstationary local quantities; these integrals are macroscopic fluxes and production rates. In general the dynamics of these integrals are not adequately described by linear equations, though in special cases they can be so described.
The Onsager relations
{{#invoke:mainmain}} Following Section III of Rayleigh (1873),^{[4]} Onsager (1931, I)^{[5]} showed that in the regime where both the flows () are small and the thermodynamic forces () vary slowly, the rate of creation of entropy is linearly related to the flows:
and the flows are related to the gradient of the forces, parametrized by a matrix of coefficients conventionally denoted :
from which it follows that:
The second law of thermodynamics requires that the matrix be positive definite. Statistical mechanics considerations involving microscopic reversibility of dynamics imply that the matrix is symmetric. This fact is called the Onsager reciprocal relations.
Speculated thermodynamic extremum principles for energy dissipation and entropy production
Jou, CasasVazquez, Lebon (1993)^{[12]} note that classical nonequilibrium thermodynamics "has seen an extraordinary expansion since the second world war", and they refer to the Nobel prizes for work in the field awarded to Lars Onsager and Ilya Prigogine. Martyushev and Seleznev (2006)^{[34]} note the importance of entropy in the evolution of natural dynamical structures: "Great contribution has been done in this respect by two scientists, namely Clausius, ... , and Prigogine." Prigogine in his 1977 Nobel Lecture^{[35]} said: "... nonequilibrium may be a source of order. Irreversible processes may lead to a new type of dynamic states of matter which I have called “dissipative structures”." Glansdorff and Prigogine (1971)^{[11]} wrote on page xx: "Such 'symmetry breaking instabilities' are of special interest as they lead to a spontaneous 'selforganization' of the system both from the point of view of its space order and its function."
Analyzing the RayleighBénard convection cell phenomenon, Chandrasekhar (1961)^{[36]} wrote "Instability occurs at the minimum temperature gradient at which a balance can be maintained between the kinetic energy dissipated by viscosity and the internal energy released by the buoyancy force." With a temperature gradient greater than the minimum, viscosity can dissipate kinetic energy as fast as it is released by convection due to buoyancy, and a steady state with convection is stable. The steady state with convection is often a pattern of macroscopically visible hexagonal cells with convection up or down in the middle or at the 'walls' of each cell, depending on the temperature dependence of the quantities; in the atmosphere under various conditions it seems that either is possible. (Some details are discussed by Lebon, Jou, and CasasVásquez (2008)^{[3]} on pages 143158.) With a temperature gradient less than the minimum, viscosity and heat conduction are so effective that convection cannot keep going.
Glansdorff and Prigogine (1971)^{[11]} on page xv wrote "Dissipative structures have a quite different [from equilibrium structures] status: they are formed and maintained through the effect of exchange of energy and matter in nonequilibrium conditions." They were referring to the dissipation function of Rayleigh (1873)^{[4]} that was used also by Onsager (1931, I,^{[5]} 1931, II^{[37]}). On pages 78–80 of their book^{[11]} Glansdorff and Prigogine (1971) consider the stability of laminar flow that was pioneered by Helmholtz; they concluded that at a stable steady state of sufficiently slow laminar flow, the dissipation function was minimum.
These advances have led to proposals for various extremal principles for the "selforganized" régimes that are possible for systems governed by classical linear and nonlinear nonequilibrium thermodynamical laws, with stable stationary régimes being particularly investigated. Convection introduces effects of momentum which appear as nonlinearity in the dynamical equations. In the more restricted case of no convective motion, Prigogine wrote of "dissipative structures". Šilhavý (1997)^{[38]} offers the opinion that "... the extremum principles of [equilibrium] thermodynamics ... do not have any counterpart for [nonequilibrium] steady states (despite many claims in the literature)."
Prigogine’s proposed theorem of minimum entropy production for very slow purely diffusive transfer
In 1945 Prigogine ^{[39]} (see also Prigogine (1947)^{[40]}) proposed a “Theorem of Minimum Entropy Production” which applies only to the purely diffusive linear regime, with negligible inertial terms, near a stationary thermodynamically nonequilibrium state. Prigogine's proposal is that the rate of entropy production is locally minimum at every point. The proof offered by Prigogine is open to serious criticism.^{[7]} A critical and unsupportive discussion of Prigogine's proposal is offered by Grandy (2008).^{[2]} It has been shown by Barbera that the total whole body entropy production cannot be minimum, but this paper did not consider the pointwise minimum proposal of Prigogine.^{[41]} A proposal closely related to Prigogine's is that the pointwise rate of entropy production should have its maximum value minimized at the steady state. This is compatible, but not identical, with the Prigogine proposal.^{[42]} Moreover, N. W. Tschoegl proposes a proof, perhaps more physically motivated than Prigogine's, that would if valid support the conclusion of Helmholtz and of Prigogine, that under these restricted conditions, the entropy production is at a pointwise minimum.^{[43]}
Faster transfer with convective circulation: second entropy
In contrast to the case of sufficiently slow transfer with linearity between flux and generalized force with negligible inertial terms, there can be heat transfer that is not very slow. Then there is consequent nonlinearity, and heat flow can develop into phases of convective circulation. In these cases, the time rate of entropy production has been shown to be a nonmonotonic function of time during the approach to steady state heat convection. This makes these cases different from the nearthermodynamicequilibrium regime of veryslowtransfer with linearity. Accordingly, the local time rate of entropy production, defined according to the local thermodynamic equilibrium hypothesis, is not an adequate variable for prediction of the time course of farfromthermodynamic equilibrium processes. The principle of minimum entropy production is not applicable to these cases.
To cover these cases, there is needed at least one further state variable, a nonequilibrium quantity, the socalled second entropy. This appears to be a step towards generalization beyond the classical second law of thermodynamics, to cover nonequilibrium states or processes. The classical law refers only to states of thermodynamic equilibrium, and local thermodynamic equilibrium theory is an approximation that relies upon it. Still it is invoked to deal with phenomena near but not at thermodynamic equilibrium, and has some uses then. But the classical law is inadequate for description of the time course of processes far from thermodynamic equilibrium. For such processes, a more powerful theory is needed, and the second entropy is part of such a theory.^{[44]}^{[45]}
Speculated principles of maximum entropy production and minimum energy dissipation
Onsager (1931, I)^{[5]} wrote: "Thus the vector field J of the heat flow is described by the condition that the rate of increase of entropy, less the dissipation function, be a maximum." Careful note needs to be taken of the opposite signs of the rate of entropy production and of the dissipation function, appearing in the lefthand side of Onsager's equation (5.13) on Onsager's page 423.^{[5]}
Although largely unnoticed at the time, Ziegler proposed an idea early with his work in the mechanics of plastics in 1961,^{[46]} and later in his book on thermomechanics revised in 1983,^{[9]} and in various papers (e.g., Ziegler (1987),^{[47]}). Ziegler never stated his principle as a universal law but he may have intuited this. He demonstrated his principle using vector space geometry based on an “orthogonality condition” which only worked in systems where the velocities were defined as a single vector or tensor, and thus, as he wrote^{[9]} at p. 347, was “impossible to test by means of macroscopic mechanical models”, and was, as he pointed out, invalid in “compound systems where several elementary processes take place simultaneously”.
In relation to the earth's atmospheric energy transport process, according to Tuck (2008),^{[48]} "On the macroscopic level, the way has been pioneered by a meteorologist (Paltridge 1975,^{[49]} 2001^{[50]})." Initially Paltridge (1975)^{[49]} used the terminology "minimum entropy exchange", but after that, for example in Paltridge (1978),^{[51]} and in Paltridge (1979),^{[52]} he used the now current terminology "maximum entropy production" to describe the same thing. The logic of Paltridge's earlier work is open to serious criticism.^{[2]} Nicolis and Nicolis (1980) ^{[53]} discuss Paltridge's work, and they comment that the behaviour of the entropy production is far from simple and universal. Later work by Paltridge focuses more on the idea of a dissipation function than on the idea of rate of production of entropy.^{[50]}
Sawada (1981),^{[54]} also in relation to the Earth's atmospheric energy transport process, postulating a principle of largest amount of entropy increment per unit time, cites work in fluid mechanics by Malkus and Veronis (1958)^{[55]} as having "proven a principle of maximum heat current, which in turn is a maximum entropy production for a given boundary condition", but this inference is not logically valid. Again investigating planetary atmospheric dynamics, Shutts (1981)^{[56]} used an approach to the definition of entropy production, different from Paltridge's, to investigate a more abstract way to check the principle of maximum entropy production, and reported a good fit.
Prospects
Until recently, prospects for useful extremal principles in this area have seemed clouded. C. Nicolis (1999)^{[57]} concludes that one model of atmospheric dynamics has an attractor which is not a regime of maximum or minimum dissipation; she says this seems to rule out the existence of a global organizing principle, and comments that this is to some extent disappointing; she also points to the difficulty of finding a thermodynamically consistent form of entropy production. Another top expert offers an extensive discussion of the possibilities for principles of extrema of entropy production and of dissipation of energy: Chapter 12 of Grandy (2008)^{[2]} is very cautious, and finds difficulty in defining the 'rate of internal entropy production' in many cases, and finds that sometimes for the prediction of the course of a process, an extremum of the quantity called the rate of dissipation of energy may be more useful than that of the rate of entropy production; this quantity appeared in Onsager's 1931^{[5]} origination of this subject. Other writers have also felt that prospects for general global extremal principles are clouded. Such writers include Glansdorff and Prigogine (1971), Lebon, Jou and CasasVásquez (2008), and Šilhavý (1997), as noted in the Wikipedia article on Extremal principles in nonequilibrium thermodynamics.
A recent proposal may perhaps bypass those clouded prospects.^{[44]}
Applications of nonequilibrium thermodynamics
Nonequilibrium thermodynamics has been successfully applied to describe biological systems such as Protein Folding/unfolding and transport through membranes.
See also
 Dissipative system
 Entropy production
 Extremal principles in nonequilibrium thermodynamics
 Selforganization
 Autocatalytic reactions and order creation
 Selforganizing criticality
 BogoliubovBornGreenKirkwoodYvon hierarchy of equations
 Boltzmann equation
 Vlasov equation
 Maxwell's demon
 Information entropy
 Constructal theory
 Spontaneous symmetry breaking
References
 ↑ Fowler, R., Guggenheim, E.A. (1939). Statistical Thermodynamics, Cambridge University Press, Canbridge UK, page vii.
 ↑ ^{2.0} ^{2.1} ^{2.2} ^{2.3} Grandy, W.T., Jr (2008). Entropy and the Time Evolution of Macroscopic Systems. Oxford University Press. ISBN 9780199546176.
 ↑ ^{3.0} ^{3.1} ^{3.2} ^{3.3} ^{3.4} Lebon, G., Jou, D., CasasVázquez, J. (2008). Understanding Nonequilibrium Thermodynamics: Foundations, Applications, Frontiers, SpringerVerlag, Berlin, eISBN 9783540742524.
 ↑ ^{4.0} ^{4.1} ^{4.2} {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ ^{5.0} ^{5.1} ^{5.2} ^{5.3} ^{5.4} ^{5.5} ^{5.6} ^{5.7} {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ ^{6.0} ^{6.1} ^{6.2} Gyarmati, I. (1970). Nonequilibrium Thermodynamics. Field Theory and Variational Principles, translated by E. Gyarmati and W.F. Heinz, Springer, Berlin.
 ↑ ^{7.0} ^{7.1} ^{7.2} ^{7.3} ^{7.4} Lavenda, B.H. (1978). Thermodynamics of Irreversible Processes, Macmillan, London, ISBN 0333216164.
 ↑ Gyarmati, I. (1967/1970) Nonequilibrium Thermodynamics. Field Theory and Variational Principles, translated by E. Gyarmati and W.F. Heinz, Springer, New York, pages 414.
 ↑ ^{9.0} ^{9.1} ^{9.2} Ziegler, H., (1983). An Introduction to Thermomechanics, NorthHolland, Amsterdam, ISBN 0444865039. Cite error: Invalid
<ref>
tag; name "Ziegler 1983" defined multiple times with different content  ↑ Balescu, R. (1975). Equilibrium and Nonequilibrium Statistical Mechanics, WileyInterscience, New York, ISBN 0471046000, Section 3.2, pages 6472.
 ↑ ^{11.0} ^{11.1} ^{11.2} ^{11.3} ^{11.4} ^{11.5} Glansdorff, P., Prigogine, I. (1971). Thermodynamic Theory of Structure, Stability, and Fluctuations, WileyInterscience, London, 1971, ISBN 0471302805.
 ↑ ^{12.0} ^{12.1} ^{12.2} Jou, D., CasasVázquez, J., Lebon, G. (1993). Extended Irreversible Thermodynamics, Springer, Berlin, ISBN 3540558748, ISBN 0387558748.
 ↑ Eu, B.C. (2002). Generalized Thermodynamics. The Thermodynamics of Irreversible Processes and Generalized Hydrodynamics, Kluwer Academic Publishers, Dordrecht, ISBN 1402007884.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Prigogine, I., Defay, R. (1950/1954). Chemical Thermodynamics, Longmans, Green & Co, London, page 1.
 ↑ ^{19.0} ^{19.1} De Groot, S.R., Mazur, P. (1962). Nonequilibrium Thermodynamics, NorthHolland, Amsterdam.
 ↑ Kondepudi, D. (2008). Introduction to Modern Thermodynamics, Wiley, Chichester UK, ISBN 9780470015988, pages 333338.
 ↑ ^{21.0} ^{21.1} Balescu, R. (1975). Equilibrium and Nonequilibrium Statistical Mechanics, John Wiley & Sons, New York, ISBN 0471046000.
 ↑ ^{22.0} ^{22.1} Mihalas, D., WeibelMihalas, B. (1984). Foundations of Radiation Hydrodynamics, Oxford University Press, New York, ISBN 0195034376.
 ↑ ^{23.0} ^{23.1} Schloegl, F. (1989). Probability and Heat: Fundamentals of Thermostatistics, Freidr. Vieweg & Sohn, Brausnchweig, ISBN 3528063432.
 ↑ ^{24.0} ^{24.1} Keizer, J. (1987). Statistical Thermodynamics of Nonequilibrium Processes, SpringerVerlag, New York, ISBN 0387965017.
 ↑ Coleman, B.D., Noll, W. (1963). The thermodynamics of elastic materials with heat conduction and viscosity, Arch. Ration. Mach. Analysis, 13: 167–178.
 ↑ Kondepudi, D., Prigogine, I, (1998). Modern Thermodynamics. From Heat Engines to Dissipative Structures, Wiley, Chichester, 1998, ISBN 0471973947.
 ↑ ^{27.0} ^{27.1} Zubarev D. N.,(1974). Nonequilibrium Statistical Thermodynamics, translated from the Russian by P.J. Shepherd, New York, Consultants Bureau. ISBN 030610895X; ISBN 9780306108952.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Grandy 2004 see also [1].
 ↑ W. Greiner, L. Neise, and H. Stöcker (1997), Thermodynamics and Statistical Mechanics (Classical Theoretical Physics) ,SpringerVerlag, New York, P85, 91, 101,108,116, ISBN 0387942998.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Prigogine, I. (1977). Time, Structure and Fluctuations, Nobel Lecture.
 ↑ Chandrasekhar, S. (1961). Hydrodynamic and Hydromagnetic Stability, Clarendon Press, Oxford.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Šilhavý, M. (1997). The Mechanics and Thermodynamics of Continuous Media, Springer, Berlin, ISBN 3540583785, page 209.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Prigogine, I. (1947). Étude thermodynamique des Phenomènes Irreversibles, Desoer, Liege.
 ↑ Barbera, E. (1999). On the principle of minimum entropy production for NavierStokesFourier fluids, Continuum Mech. Thermodyn., 11: 327–330.
 ↑ Struchtrup, H., Weiss, W. (1998). Maximum of the local entropy production becomes minimal in stationary processes, Phys. Rev. Lett., 80: 5048–5051.
 ↑ Tschoegl, N.W. (2000). Fundamentals of Equilibrium and SteadyState Thermodynamics, Elsevier, Amsterdam, ISBN 0444504265, Chapter 30, pp. 213–215.
 ↑ ^{44.0} ^{44.1} {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Attard, P. (2012). NonEquilibrium Thermodynamics and Statistical Mechanics: Foundations and Applications, Oxford University Press, Oxford UK, ISBN 9780199662760.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Tuck, Adrian F. (2008) Atmospheric Turbulence: a molecular dynamics perspective, Oxford University Press. ISBN 9780199236534. See page 33.
 ↑ ^{49.0} ^{49.1} {{#invoke:Citation/CS1citation CitationClass=journal }}Template:Dead link
 ↑ ^{50.0} ^{50.1} {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}Template:Dead link
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ Sawada, Y. (1981). A thermodynamic variational principle in nonlinear nonequilibrium phenomena, Progress of Theoretical Physics 66: 6876.
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
 ↑ {{#invoke:Citation/CS1citation CitationClass=journal }}
Further reading
 Ziegler, Hans (1977): An introduction to Thermomechanics. North Holland, Amsterdam. ISBN 0444110801. Second edition (1983) ISBN 0444865039.
 Kleidon, A., Lorenz, R.D., editors (2005). Nonequilibrium Thermodynamics and the Production of Entropy, Springer, Berlin. ISBN 3540224955.
 Prigogine, I. (1955/1961/1967). Introduction to Thermodynamics of Irreversible Processes. 3rd edition, Wiley Interscience, New York.
 Zubarev D. N. (1974): Nonequilibrium Statistical Thermodynamics. New York, Consultants Bureau. ISBN 030610895X; ISBN 9780306108952.
 Keizer, J. (1987). Statistical Thermodynamics of Nonequilibrium Processes, SpringerVerlag, New York, ISBN 0387965017.
 Zubarev D. N., Morozov V., Ropke G. (1996): Statistical Mechanics of Nonequilibrium Processes: Basic Concepts, Kinetic Theory. John Wiley & Sons. ISBN 3055017080.
 Zubarev D. N., Morozov V., Ropke G. (1997): Statistical Mechanics of Nonequilibrium Processes: Relaxation and Hydrodynamic Processes. John Wiley & Sons. ISBN 3527400842.
 Tuck, Adrian F. (2008). Atmospheric turbulence : a molecular dynamics perspective. Oxford University Press. ISBN 9780199236534.
 Grandy, W.T., Jr (2008). Entropy and the Time Evolution of Macroscopic Systems. Oxford University Press. ISBN 9780199546176.
 Kondepudi, D., Prigogine, I. (1998). Modern Thermodynamics: From Heat Engines to Dissipative Structures. John Wiley & Sons, Chichester. ISBN 0471973939.
 de Groot S.R., Mazur P. (1984). NonEquilibrium Thermodynamics (Dover). ISBN 0486647412
External links
 Stephan Herminghaus' Dynamics of Complex Fluids Department at the Max Planck Institute for Dynamics and Self Organization
 Nonequilibrium Statistical Thermodynamics applied to Fluid Dynamics and Laser Physics  1992 book by Xavier de Hemptinne.
 Nonequilibrium Thermodynamics of Small Systems  PhysicsToday.org
 Into the Cool  2005 book by Dorion Sagan and Eric D. Schneider, on nonequilibrium thermodynamics and evolutionary theory.
 Thermodynamics ‘‘beyond’’ local equilibrium