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Thermophysical properties of supercritical fluids and fluid mixtures. Final technical report, December 15, 1988--December 14, 1994
This research is concerned with the development of quantitative scientific descriptions of the thermodynamic and transport properties of supercritical and subcritical fluids and fluid mixtures. It is well known that the thermophysical properties of fluids and fluid mixtures exhibit singular behavior at critical points. Asymptotically close to critical points the thermophysical properties satisfy scaling laws with universal critical exponents and universal scaling functions. However, the range of validity of these asymptotic scaling laws is very small. It has now been well established that the range of temperatures and densities where various thermophysical properties are affected is quite large. The reason is that the correlation length associated with the critical fluctuations exceeds the short-range molecular interaction range in a sizeable part of the phase diagram of fluids and fluid mixtures. The paper discusses the research accomplishments of the following: Thermodynamic properties of one-component fluids; Thermodynamic properties of fluid mixtures; Transport properties of one-component fluids; and Transport properties of fluid mixtures
A scaled fundamental equation for the thermodynamic properties of carbon dioxide in the critical region
A scaled fundamental equation is presented for the thermodynamic properties of carbon dioxide in the critical region. The equation is constructed by combining earlier experimental pressure data of Michels and co‐workers with new specific heat data obtained by one of the authors and represents the thermodynamic properties of carbon dioxide in the critical region at temperatures from 301.15 to 323 K and at densities from 290 to 595 kg/m3
Shape of crossover between mean-field and asymptotic critical behavior in a three-dimensional Ising lattice
Recent numerical studies of the susceptibility of the three-dimensional Ising
model with various interaction ranges have been analyzed with a crossover model
based on renormalization-group matching theory. It is shown that the model
yields an accurate description of the crossover function for the
susceptibility.Comment: 4 pages RevTeX + 3 PostScript figures. Uses epsf.sty and rotate.sty.
Final version; accepted for publication in Physics Letters
Critical Point Field Mixing in an Asymmetric Lattice Gas Model
The field mixing that manifests broken particle-hole symmetry is studied for
a 2-D asymmetric lattice gas model having tunable field mixing properties.
Monte Carlo simulations within the grand canonical ensemble are used to obtain
the critical density distribution for different degrees of particle-hole
asymmetry. Except in the special case when this asymmetry vanishes, the density
distributions exhibit an antisymmetric correction to the limiting
scale-invariant form. The presence of this correction reflects the mixing of
the critical energy density into the ordering operator. Its functional form is
found to be in excellent agreement with that predicted by the mixed-field
finite-size-scaling theory of Bruce and Wilding. A computational procedure for
measuring the significant field mixing parameter is also described, and its
accuracy gauged by comparing the results with exact values obtained
analytically.Comment: 10 Pages, LaTeX + 8 figures available from author on request, To
appear in Z. Phys.
Critical Viscosity Exponent for Fluids: What Happend to the Higher Loops
We arrange the loopwise perturbation theory for the critical viscosity
exponent , which happens to be very small, as a power series in
itself and argue that the effect of loops beyond two is negligible.
We claim that the critical viscosity exponent should be very closely
approximated by .Comment: 9 pages and 3 figure
Microscopic View on Short-Range Wetting at the Free Surface of the Binary Metallic Liquid Gallium-Bismuth: An X-ray Reflectivity and Square Gradient Theory Study
We present an x-ray reflectivity study of wetting at the free surface of the
binary liquid metal gallium-bismuth (Ga-Bi) in the region where the bulk phase
separates into Bi-rich and Ga-rich liquid phases. The measurements reveal the
evolution of the microscopic structure of wetting films of the Bi-rich,
low-surface-tension phase along different paths in the bulk phase diagram. A
balance between the surface potential preferring the Bi-rich phase and the
gravitational potential which favors the Ga-rich phase at the surface pins the
interface of the two demixed liquid metallic phases close to the free surface.
This enables us to resolve it on an Angstrom level and to apply a mean-field,
square gradient model extended by thermally activated capillary waves as
dominant thermal fluctuations. The sole free parameter of the gradient model,
i.e. the so-called influence parameter, , is determined from our
measurements. Relying on a calculation of the liquid/liquid interfacial tension
that makes it possible to distinguish between intrinsic and capillary wave
contributions to the interfacial structure we estimate that fluctuations affect
the observed short-range, complete wetting phenomena only marginally. A
critical wetting transition that should be sensitive to thermal fluctuations
seems to be absent in this binary metallic alloy.Comment: RevTex4, twocolumn, 15 pages, 10 figure
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