The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of [h-bar]/4pikB for a large class of strongly interacting quantum field theories whose dual description involves black holes in anti–de Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids.

Viscosity in strongly interacting quantum field theories from black hole physics

National Institute of Standards and Technology における超伝導研究及び生活

This is the eighteenth in a series of evaluated sets of rate constants, photochemical cross sections, heterogeneous parameters, and thermochemical parameters compiled by the NASA Panel for Data Evaluation. The data are used primarily to model stratospheric and upper tropospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena. The evaluation is available in electronic form from the following Internet URL: http://jpldataeval.jpl.nasa.gov/

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Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies: Evaluation Number 18

A re-parameterization of the standard TIP4P water model for use with Ewald techniques is introduced, providing an overall global improvement in water properties relative to several popular nonpolarizable and polarizable water potentials. Using high precision simulations, and careful application of standard analytical corrections, we show that the new TIP4P-Ew potential has a density maximum at approximately 1 degrees C, and reproduces experimental bulk-densities and the enthalpy of vaporization, DeltaH(vap), from -37.5 to 127 degrees C at 1 atm with an absolute average error of less than 1%. Structural properties are in very good agreement with x-ray scattering intensities at temperatures between 0 and 77 degrees C and dynamical properties such as self-diffusion coefficient are in excellent agreement with experiment. The parameterization approach used can be easily generalized to rehabilitate any water force field using available experimental data over a range of thermodynamic points.

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Development of an improved four-site water model for biomolecular simulations: TIP4P-Ew

Over the last few decades, researchers have developed a number of empirical and theoretical models for the correlation and prediction of the thermophysical properties of pure fluids and mixtures treated as pseudo-pure fluids In this paper, a survey of all the state-of-the-art formulations of thermophysical properties is presented The most-accurate thermodynamic properties are obtained from multiparameter Helmholtz-energy-explicit-type formulations For the transport properties, a wider range of methods has been employed, including the extended corresponding states method All of the thermophysical property correlations described here have been implemented into CoolProp, an open-source thermophysical property library This library is written in C++, with wrappers available for the majority of programming languages and platforms of technical interest As of publication, 110 pure and pseudo-pure fluids are included in the library, as well as properties of 40 incompressible fluids and humid air The source code for the CoolProp library is included as an electronic annex

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Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp.

We developed surrogate mixture models to represent the thermophysical properties of two samples of aviation turbine fuel Jet-A. One sample is a composite of numerous batches from multiple manufacturers and is considered to be a representative fuel. A second sample, while still meeting the fuel specifications, contained a lower than normal aromatic content and was selected to demonstrate some of the compositional variability seen among different batches of Jet-A fuel. A surrogate for each fuel was developed with a procedure that incorporated experimental data for the density, sound speed, viscosity, thermal conductivity, cetane number, and the volatility (as indicated by advanced distillation curves) for samples of the two fuels. The surrogates are simple mixtures containing eight or fewer components, yet they can represent with low uncertainty the thermophysical properties of actual real fluids that are very complex mixtures of hundreds of components.

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Surrogate Mixture Models for the Thermophysical Properties of Aviation Fuel Jet-A

A new formulation describing the thermodynamic properties of nitrogen has been developed. New data sets which have been used to improve the representation of the p–ρ–T surface of gaseous, liquid and supercritical nitrogen, including the saturated states are now available. New measurements on the speed of sound from spherical resonators have been used to improve the accuracy of caloric properties in gaseous and supercritical nitrogen. State-of-the-art algorithms for the optimization of the mathematical structure of the equation and special functional forms for an improved description of the critical region were used to represent even the most accurate data within their experimental uncertainty. The uncertainty in density of the new reference equation of state ranges from ±0.01% between 270 and 350 K at pressures less than 12MPa, within ±0.02% over all other temperatures less than 550 K and pressures less than 12 MPa, and up to a maximum of ±0.6% at the highest pressures. The equation is valid from the triple point to temperatures of 1000 K and pressures up to 2200 MPa. The new formulation yields a reasonable extrapolation up to the limits of chemical stability of nitrogen as indicated by comparison to experimental shock tube data. Constraints regarding the structure of the equation ensure reasonable extrapolated properties up to temperatures and pressures of 5000 K and 25 GPa. For typical calibration applications, the new reference equation is supplemented by a simple but also highly accurate formulation, valid only for supercritical nitrogen between 270 and 350 K at pressures up to 30 MPa.

A Reference Quality Equation of State for Nitrogen

We developed a surrogate mixture model to represent the physical properties of a coal-derived liquid fuel using only information obtained from a gas chromatography−mass spectrometry analysis of the fuel and a recently developed “advanced distillation curve”. We then predicted the density, speed of sound, and viscosity of the fuel and compared them to limited experimental data. The surrogate contains five components (n-propylcyclohexane, trans-decalin, α-methyldecalin, bicyclohexane, and n-hexadecane), yet comparisons to limited experimental data demonstrate that the model is able to represent the density, sound speed, and viscosity to within 1, 4, and 5%, respectively.

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Chemically Authentic Surrogate Mixture Model for the Thermophysical Properties of a Coal-Derived Liquid Fuel

Mixture models explicit in Helmholtz energy have been developed to calculate the thermodynamic properties of refrigerant mixtures containing R-32, R-125, R-134a, R143a, and R-152a The Helmholtz energy of the mixture is the sum of the ideal gas contribution, the compressibility (or real fluid) contribution, and the contribution from mixing The independent variables are the density, temperature, and composition The model may be used to calculate the thermodynamic properties of mixtures, including dew and bubble point properties, within the experimental uncertainties of the available measured properties It incorporates the most accurate equations of state available for each pure fluid The estimated uncertainties of calculated properties are 01% in density and 05% in heat capacities and in the speed of sound Calculated bubble point pressures have typical uncertainties of 05%

Equations of State for Mixtures of R-32, R-125, R-134a, R-143a, and R-152a

We present an equation-of-state approach to modeling the thermodynamic properties of a biodiesel fuel. Preliminary Helmholtz-type equations of state were developed with limited experimental data for five fatty acid methyl esters (FAMEs) that are the primary constituents of soy-based biodiesel fuel, namely, methyl palmitate, methyl stearate, methyl oleate, methyl linoleate, and methyl linolenate. These components were combined in a mixture model using ideal mixing to represent the thermodynamic properties of a biodiesel fuel. We performed limited experimental measurements on the density, sound speed, and initial boiling point of two biodiesel fuel samples and compared the results with the model.

Eric W. Lemmon

Papers

Surrogate Mixture Models for the Thermophysical Properties of Aviation Fuel Jet-A

A Reference Quality Equation of State for Nitrogen

Chemically Authentic Surrogate Mixture Model for the Thermophysical Properties of a Coal-Derived Liquid Fuel

Equations of State for Mixtures of R-32, R-125, R-134a, R-143a, and R-152a

Model for the Thermodynamic Properties of a Biodiesel Fuel