Author
Norman F. Carnahan
Other affiliations: University of Oklahoma, Union Carbide
Bio: Norman F. Carnahan is an academic researcher from Rice University. The author has contributed to research in topics: Equation of state & Asphaltene. The author has an hindex of 12, co-authored 20 publications receiving 7104 citations. Previous affiliations of Norman F. Carnahan include University of Oklahoma & Union Carbide.
Topics: Equation of state, Asphaltene, Hard spheres, Shape factor, Oil sands
Papers
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TL;DR: In this paper, a new equation of state for rigid spheres has been developed from an analysis of the reduced virial series, which possesses superior ability to describe rigid-sphere behavior compared with existing equations.
Abstract: A new equation of state for rigid spheres has been developed from an analysis of the reduced virial series. Comparisons with existing equations show that the new formula possesses superior ability to describe rigid‐sphere behavior.
4,659 citations
TL;DR: In this article, an equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus-Yevick integral equation.
Abstract: An equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus–Yevick integral equation for the mixture of hard spheres. Compressibility and other equilibrium properties of the binary mixtures of hard spheres are calculated and they are compared with the related machine‐calculated (Monte Carlo and molecular dynamics) data. The comparison shows excellent agreement between the proposed equation of state and the machine‐calculated data.
1,894 citations
TL;DR: In this paper, an improved expression for intermolecular repulsions in equations of state is presented, where the rigid-sphere fluid is used as the model of repulsion behavior in real fluids.
Abstract: This investigation demonstrates the advantages of an improved expression for intermolecular repulsions in equations of state. A highly accurate equation of state for the rigid-sphere fluid is used as the model of repulsion behavior in real fluids. A method for general usage of this new rigid-sphere equation in real fluid models is presented via reformulation of van der Waal's equation using the accurate new rigid-sphere equation to describe repulsion effects. To test this reformulation, properties of methane, ethane, propane, n-butane, isobutane, hydrogen sulfide, nitrogen, ethylene, acetylene, methyl chloride, cyclohexane, pentane and octane have been calculated. The advantage of using the accurate rigid-sphere equation was demonstrated by the general improvement in calculated properties relative to the original van der Waals and Redlich-Kwong equations. Calculations of enthalpy departures for mixtures of nitrogen and methane, propane and methane, pentane and cyclohexane, and pentane and octane also indicated the desirability of using the accurate rigid-sphere equation to describe repulsion effects in mixtures.
255 citations
TL;DR: In this article, the excess thermodynamic properties for a rigid-sphere fluid have been calculated with an accurate equation of state, and values of (PV, NkT), (H,−H°) and (S,−S°) are reported for a wide range of fluid density.
Abstract: The excess thermodynamic properties for a rigid‐sphere fluid have been calculated with an accurate equation of state. Values of (PV / NkT), and (H − H°) / RT, (S − S°) / R, (G − G°) / RT, and (f / P) are reported for a wide range of fluid density.
189 citations
TL;DR: In this paper, a simple experimental technique, referred to as the filter drop spreading method, was used to detect the onset of flocculation quite accurately for crude oil mixtures and for mixtures of crude oils plus additives.
Abstract: Experimental results confirm that resins isolated from Boscan crude oil have a stabilizing effect on asphaltenes in Hamaca crude oil and in Boscan crude oil. A simple experimental technique, referred to as the filter drop spreading method, was used to detect the onset of flocculation quite accurately for crude oil mixtures and for mixtures of crude oils plus additives.
119 citations
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TL;DR: This paper presents a meta-modelling procedure called "Continuum Methods within MD and MC Simulations 3072", which automates the very labor-intensive and therefore time-heavy and expensive process of integrating discrete and continuous components into a discrete-time model.
Abstract: 6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072
13,286 citations
TL;DR: High entropy alloys (HEAs) are barely 12 years old as discussed by the authors, and the field has stimulated new ideas and inspired the exploration of the vast composition space offered by multi-principal element alloys.
4,693 citations
TL;DR: In this paper, a modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid, which is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers.
Abstract: A modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid. With conventional one-fluid mixing rules, the equation of state is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers. The three pure-component parameters required for nonassociating molecules were identified for 78 substances by correlating vapor pressures and liquid volumes. The equation of state gives good fits to these properties and agrees well with caloric properties. When applied to vapor−liquid equilibria of mixtures, the equation of state shows substantial predictive capabilities and good precision for correlating mixtures. Comparisons to the SAFT version of Huang and Radosz reveal a clear improvement of the proposed model. A brief comparison with the Peng−Robinson model is also given for vapor−liquid equilibria of binary systems, confirming the good performance of the suggested equation of state. ...
2,739 citations
TL;DR: In this paper, the authors studied the flow of an idealized granular material consisting of uniform smooth, but nelastic, spherical particles using statistical methods analogous to those used in the kinetic theory of gases.
Abstract: The flow of an idealized granular material consisting of uniform smooth, but nelastic, spherical particles is studied using statistical methods analogous to those used in the kinetic theory of gases. Two theories are developed: one for the Couette flow of particles having arbitrary coefficients of restitution (inelastic particles) and a second for the general flow of particles with coefficients of restitution near 1 (slightly inelastic particles). The study of inelastic particles in Couette flow follows the method of Savage & Jeffrey (1981) and uses an ad hoc distribution function to describe the collisions between particles. The results of this first analysis are compared with other theories of granular flow, with the Chapman-Enskog dense-gas theory, and with experiments. The theory agrees moderately well with experimental data and it is found that the asymptotic analysis of Jenkins & Savage (1983), which was developed for slightly inelastic particles, surprisingly gives results similar to the first theory even for highly inelastic particles. Therefore the ‘nearly elastic’ approximation is pursued as a second theory using an approach that is closer to the established methods of Chapman-Enskog gas theory. The new approach which determines the collisional distribution functions by a rational approximation scheme, is applicable to general flowfields, not just simple shear. It incorporates kinetic as well as collisional contributions to the constitutive equations for stress and energy flux and is thus appropriate for dilute as well as dense concentrations of solids. When the collisional contributions are dominant, it predicts stresses similar to the first analysis for the simple shear case.
2,631 citations
TL;DR: In this article, an equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus-Yevick integral equation.
Abstract: An equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus–Yevick integral equation for the mixture of hard spheres. Compressibility and other equilibrium properties of the binary mixtures of hard spheres are calculated and they are compared with the related machine‐calculated (Monte Carlo and molecular dynamics) data. The comparison shows excellent agreement between the proposed equation of state and the machine‐calculated data.
1,894 citations