Nonequilibrium phenomena in dense polyatomic fluids. I. Transport coefficients for axially symmetric (polar) molecules

Landauer's blowtorch effect as a thermodynamic cross process: Brownian cooling

The local heating of a selected region in a double-well potential alters the relative stability of the two wells and gives rise to an enhancement of population transfer to the cold well. We show that this Landauer's blowtorch effect may be considered in the spirit of a thermodynamic cross process linearly connecting the flux of particles and the thermodynamic force associated with the temperature difference and consequently ensuring the existence of a reverse cross effect. This reverse effect is realized by directing the thermalized particles in a double-well potential by application of an external bias from one well to the other, which suffers cooling.

The Enskog-type theory of the velocity autocorrelations in the two-dimensional nematic of hard needles

As it was shown from molecular dynamics of two-dimensional hard needles, the uniaxial velocity autocorrelation function (VACF) of this system exhibits a two time scale character. This corresponds to the symmetry of the particles. In this paper we provide a theory of the Enskog type that corroborates the idea that the VACF can be successfully described as a sum of two single decays. From the comparison between molecular dynamics and theoretical results, we show that the Enskog approach is a satisfactory kinetic theory, which functions as well in the nematic as in the isotropic phase. Different properties of VACFs have been investigated, in particular, the dependence on the orientational order, temperature, and particles' inertness.

Kinetic theory of dense fluids of rigid biaxial ellipsoids

The transport equation for a one-particle distribution function f of a pure and dense fluid composed of hard biaxial ellipsoids has been derived by the Enskog method through a modification of the Taxman equation which describes the corresponding low-density fluid. The equation for f has been utilized in obtaining approximate equations of continuity, linear momentum, and energy of the dense fluid, and has then been solved through the Enskog infinite series expansion technique, and a second-order approximate formula for f has been achieved. Using this, results are derived for the hydrodynamic pressure, shear and bulk viscosity coefficients, and heat conductivity of the fluid. Fast exchange of energy between the translational and rotational motions is assumed throughout the calculation. The quantities ultimately appearing in the results, which cannot further be reduced analytically and require numerical evaluation, are the four-dimensional quadratures over the orientational coordinates of two interacting rigid ellipsoidal molecules. In the appropriate limit, all results reduce to those obtained by Enskog for a dense fluid of hard spheres, and a first-order modified Eucken-type formula for the dense fluid emerges.