New stochastic models of thermodiffusion are constructed and their hydrodynamical limits are studied through a first order Chapman-Enskog expansion. These models differ from earlier ones by taking into account all first order contributions proportional to the temperature gradient and, thus, allow for both positive and negative Soret coefficients, in accordance with observations.

The derivation of the multicomponent diffusion law is revisited. Following Furry Am. J. Phys. 16, 63 1948 , Williams Am. J. Phys. 26, 467 1958 ; Combustion Theory, 2nd ed. Benjamin/ Cummings , Menlo Park, CA,1985 heuristically rederived the classical kinetic theory results using macroscopic equations, and pointed out that the dynamics of the mixture fluid had been assumed inviscid. This paper g...

We investigated the thermal diffusion behavior of aqueous solutions of monosaccharides with the infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS) setup. As monosaccharides, we studied the three aldohexoses glucose, galactose, and mannose and the two ketohexoses sorbose and fructose. All sugars have the same molecular weight, but their structures differ as well as some physical pr...

Accumulated experimental information is used to assess the possible significance of thermal diffusion to mass transport in living matter. Possible thermal gradients across membranes, a single living cell, and an ensemble of such cells (e.g. an organ, tumor, etc.) are estimated. The corresponding model calculations, although not describing the biological process in detail, lead to conclusions ab...

New molecular and thermal diffusion coefficients of binary mixtures of normal decane-normal alkanes and methylnaphthalene-normal alkanes are measured at atmospheric pressure and T = 25 degrees C. The normal alkanes used in this work include nC5-nC20. Thermal diffusion coefficients were measured in a thermogravitational column. Molecular diffusion coefficients were measured using an open-ended c...

An analytical solution for one-dimensional diffusion of chemicals under coupled chemical and thermal potentials is presented. The theoretical formulation considered includes heat conduction and chemical diffusion due to both molecular and thermal diffusion potentials. Laplace transformation technique has been used to derive the analytical solution to the problem in a semi-infinite domain. The r...

New thermal diffusion coefficients of binary mixtures are measured for n-decane-n-alkanes and 1-methylnaphthalene-n-alkanes with 25 and 75 wt % at 25 degrees C and 1 atm using the thermogravitational column technique. The alkanes range from n-pentane to n-eicosane. The new results confirm the recently observed nonmonotonic behavior of thermal diffusion coefficients with molecular weight for bin...

The Ludwig-Soret effect (that is, thermal diffusion) describes the concentration gradient in a mixture under a temperature gradient. The effect is quantified by the Soret coefficient, which is in turn related to the molecular and thermal diffusion coefficients of a mixture. Thermal diffusion is important in a myriad of applications, such as in petroleum reservoirs, material sciences, oceanograp...

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