Thermodynamic Transport Coefficients Research Articles

Determining all thermodynamic transport coefficients for an interacting large N quantum field theory

Thermodynamic transport coefficients can be calculated directly from quantum field theory without requiring analytic continuation to real time. We determine all second-order thermodynamic transport coefficients for the uncharged N-component massless (critical) scalar field theory with quartic interaction in the large N limit, for any value of the coupling. We find that in the large N limit, all thermodynamic transport coefficients for the interacting theory can be expressed analytically in terms of the in-medium mass and sums over modified Bessel functions. We expect our technique to allow a similar determination of all thermodynamic transport coefficients for all theories that are solvable in the large N limit, including certain gauge theories.

Equilibrium thermodynamic susceptibilities for a dense degenerate Dirac field

Parity preserving relativistic fluids in four spacetime dimensions admit seven independent thermodynamic susceptibilities at the second order in the hydrodynamic derivative expansion. We compute all parity-even second order thermodynamic susceptibilities for a free massive Dirac field at zero temperature and a nonzero chemical potential, based on the Kubo formulas reported in P. Kovtun and A. Shukla, Kubo formulas for thermodynamic transport coefficients, J. High Energy Phys. 10 (2018) 007. We also compute the second order constitutive relations for the energy-momentum tensor and the conserved current in the absence of external gauge fields.

Kubo formulas for thermodynamic transport coefficients

Uncharged relativistic fluids in 3+1 dimensions have three independent thermodynamic transport coefficients at second order in the derivative expansion. Fluids with a single global U(1) current have nine, out of which seven are parity preserving. We derive the Kubo formulas for all nine thermodynamic transport coefficients in terms of equilibrium correlation functions of the energy-momentum tensor and the current. All parity-preserving coefficients can be expressed in terms of two-point functions in flat space without external sources, while the parity-violating coefficients require three-point functions. We use the Kubo formulas to compute the thermodynamic coefficients in several examples of free field theories.

Osmotic Coefficients of the System NH4Cl + (NH4)2SO4 + H2O at 298.15 K and Calculation of Onsager Transport Coefficients

Osmotic coefficients are reported for the system NH4Cl + (NH4)2SO4 + H2O at 298.15 K over a wide range of concentrations. Scatchard’s mixed electrolyte equation is used to fit these data with six fitting parameters, bij. For comparison, we insert extended Debye−Huckel equations and separately Pitzer’s equations as the necessary binary salt equations within Scatchard’s equation. Three sets of the six bij are obtained in each case from fits with two subsets and the full set of the osmotic coefficients. We examine the consequence of including different binary osmotic coefficient expression equations and applying different data ranges in these fits. The results are combined with available ternary diffusion coefficients to calculate and report solvent frame thermodynamic transport coefficients, (Lij)0. These are intercompared relative to the Onsager Reciprocal Relations requirement. Finally, we use Pitzer’s mixed electrolyte equation to calculate thermodynamic properties of the ternary system directly and to c...

The role of irreversible thermodynamics and rheology in the regelation-flow phenomenon

Recent experimental evidence indicates that the thermodynamic behaviour of complex visco-plastic materials such as frozen soils and ice cannot be viewed as independent of its rheological behaviour 1 1 Wood and Williams (1985a); Williams and Wood (1985). . This paper shows the manner in which the linkages are established for a very simple system such as the ice sandwich. The ice sandwich is a practical demonstration of the regelation-flow phenomenon. The experiment is discussed in several configurations including pressure-induced regelation and thermally-induced regelation. The system is driven toward restoring thermodynamic equilibrium between the ice and water at the respective interfaces, which is defined by the Clausius-Clapeyron equation. Equilibrium conditions, however, are never achieved because of continuous ice deformation in the direction of lower ice pressure, thus the need for irreversible thermodynamics in describing the process. Thermodynamic transport coefficients, derived from irreversible theory, are expressed as a function of the “apparent” thermal and hydraulic conductivities as measured in an ice sandwich permeameter, and interpreted with regard to their potential measurement in an experiment. The thermodynamic transport coefficients are then related to the rheological properties of the ice. Steady-state creep behaviour is assumed for the ice. This is reasonable for the conditions which occur in the ice sandwich and is also confirmed by experimental results. Various hypothetical scenarios are discussed for different types of ice behaviour including “plug” (rigid), “quasi-viscous” (liquid-like) and plasto-viscous (intermediate) behaviour. These scenarios are interpreted with regard to results of recent experiments of thermally-induced regelation. Finally, the implications of the analysis with respect to establishing linkages between the thermodynamic and the rheological behaviour of frozen soils are discussed.

Study of the morphology and determination of the transport coefficients for reverse osmosis membranes

Experiments were carried out to determine the thermodynamic transport coefficients ( L p, σ, ω) of cellulose acetate membranes, as well as the relationship between these coefficients and the conditions in which the membranes are prepared, the study being extended to a new type of membrane that was recently perfected. The relationship between the rejection and the reflection coefficients of these membranes was also studied. The experiments confirmed that the evaporation phase and the heating phase of the preparation have a rather marked effect on the transport coefficients of cellulose acetate membranes, σ values were found to be very low compared with rejection values, due probably to the modifications that the pressure induces in the structure of the membrane during the rejection determination.

A reappraisal of thermodynamic transport coefficients in Nitella cell walls

A reanalysis of the published thermodynamic transport coefficients has led to the conclusion that the contribution of Nitella cell walls to the electroosmotic efficiency of the wall – membrane complex in living Nitella cells has been incorrectly estimated. When the e-o efficiency observed in the living Nitella cell is less than 100 moles Faraday−1 the observed value is an overestimate if attributed to the membrane alone; when the e-o efficiency observed is over 100 moles Faraday−1 the value is an underestimate of the e-o in the membrane. A more detailed analysis of the salt concentration dependence of LPE (the electrokinetic coefficient) and of LPE2/LEELPP (the relative thermodynamic efficiency of electroosmosis) is given. It is found that LPE2/LEELPP reaches a peak efficiency (about 0.6) at about the saline concentration of pond water and xylem sap. It is concluded that the suggestion of Briggs that the electroosmosis observed in living Nitella cells may be a property of the cell wall alone is unlikely to be true.