Recalculation of the friction constant and transport coefficients of liquid argon from the Rice-Allnatt theory

1971 ◽  
Vol 24 (2) ◽  
pp. 225 ◽  
Author(s):  
AF Collings ◽  
LA Woolf
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Distribution Function ◽  
Shear Viscosity ◽  
Transport Coefficients ◽  
Liquid Argon ◽  
Viscosity Data ◽  
Liquid Region ◽  
Linear Trajectory ◽  
Momentum And Heat Transfer

The linear trajectory approximation of the ?soft? friction constant in the Rice-Allnatt theory of transport has been computed with specific attention to the lower limit of the integral. The results are significantly different from the Palyvos-Davis values for ζS in the dense gas region but agree within 2% in the liquid region. The Rice- Allnatt expressions for the coefficients of shear viscosity and thermal conductivity have been simplified and a correction of a numerical error in the collisional contributions to momentum and heat transfer is made. The coefficients D, η, and λ have been calculated for the corrected ζS and related expressions. No significant change in D is obtained, but a worsening of agreement with experimental viscosities and thermal conductivities occurs. Conversely, a better prediction of the ratio mλ/kη is obtained. More recent viscosity data for liquid argon indicate the theory is less satisfactory than has previously been considered. These results suggest that any improvement of this class of theory can only come through the use of a better representation of the radial distribution function.

scholarly journals Transport Coefficients of Hyperonic Neutron Star Cores

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 203
Author(s):  
Peter Shternin ◽  
Isaac Vidaña
Keyword(s):  
Thermal Conductivity ◽  
Neutron Star ◽  
Shear Viscosity ◽  
Transport Coefficients ◽  
Dense Matter ◽  
Baryon Number ◽  
Nucleon Nucleon ◽  
Total Thermal Conductivity ◽  
Nucleon Force ◽  
Density Region

We consider transport properties of the hypernuclear matter in neutron star cores. In particular, we calculate the thermal conductivity, the shear viscosity, and the momentum transfer rates for npΣ−Λeμ composition of dense matter in β–equilibrium for baryon number densities in the range 0.1–1 fm−3. The calculations are based on baryon interactions treated within the framework of the non-relativistic Brueckner-Hartree-Fock theory. Bare nucleon-nucleon (NN) interactions are described by the Argonne v18 phenomenological potential supplemented with the Urbana IX three-nucleon force. Nucleon-hyperon (NY) and hyperon-hyperon (YY) interactions are based on the NSC97e and NSC97a models of the Nijmegen group. We find that the baryon contribution to transport coefficients is dominated by the neutron one as in the case of neutron star cores containing only nucleons. In particular, we find that neutrons dominate the total thermal conductivity over the whole range of densities explored and that, due to the onset of Σ− which leads to the deleptonization of the neutron star core, they dominate also the shear viscosity in the high density region, in contrast with the pure nucleonic case where the lepton contribution is always the dominant one.

scholarly journals Inverse Chapman–Enskog Derivation of the Thermohydrodynamic Lattice-BGK Model for the Ideal Gas

1998 ◽  
Vol 09 (08) ◽  
pp. 1231-1245 ◽  
Author(s):  
B. M. Boghosian ◽  
P. V. Coveney
Keyword(s):  
Thermal Conductivity ◽  
Distribution Function ◽  
Relaxation Time ◽  
Equilibrium Distribution ◽  
Transport Coefficients ◽  
Ideal Gas ◽  
Equilibrium Distribution Function ◽  
Bgk Model ◽  
Constant Relaxation Time ◽  
The Ideal

A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the equilibrium distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the equilibrium distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the equilibrium distribution function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

scholarly journals On heat transfer of weakly compressible power-law flows

2017 ◽  
Vol 21 (6 Part B) ◽  
pp. 2709-2718
Author(s):  
Botong Li ◽  
Liangliang Zhu ◽  
Liancun Zheng ◽  
Wei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Power Law ◽  
Conductivity Model ◽  
Weakly Compressible ◽  
Power Law Fluids ◽  
Momentum And Heat Transfer ◽  
Thermal Conductivity Model ◽  
Dilatant Fluid

This paper completes a numerical research on steady momentum and heat transfer in power-law fluids in a channel. Weakly compressible laminar fluids are studied with no slip at the walls and uniform wall temperatures. The full governing equations are solved by continuous finite element method. Three thermal conductivity models are adopted in this paper, that is, constant thermal conductivity model, thermal conductivity varying as a function of temperature gradient, and a modified temperature-gradient-dependent thermal conductivity model. The results are compared with each other and the physical characteristics for values of parameters are also discussed in details. It is shown that the velocity curve from the solution becomes straight at higher power-law index. The effects of Reynolds numbers on the dilatant fluid and the pseudo-plastic look similar to each other and their trends can be easily predicted. Furthermore, for different models, the temperature curves also present pseudo-plastic and dilatant properties.

On the transport properties of a Van der Waals gas near the critical point

1968 ◽  
Vol 46 (24) ◽  
pp. 2821-2841 ◽  
Author(s):  
Luis de Sobrino
Keyword(s):  
Thermal Conductivity ◽  
Time Dependence ◽  
Critical Point ◽  
Bulk Viscosity ◽  
Shear Viscosity ◽  
Van Der Waals ◽  
Transport Coefficients ◽  
Hydrodynamic Equations ◽  
Van Der Waals Gas ◽  
Critical Fluctuations

A calculation of the critical anomalies of the transport coefficients of a simple fluid based on a microscopic model of a nonequilibrium Van der Waals gas is presented. It is found that, in the gas region, the anomalous bulk viscosity behaves as (T – Tc)−2. Both the anomalous thermal conductivity and shear viscosity behave as In (T – Tc)−1, but the anomaly in the shear viscosity is much smaller than the anomaly in the thermal conductivity. The results appear to indicate that previous calculations, in which the time dependence of the critical fluctuations is obtained from hydrodynamic equations, are not valid.

Transport coefficients of the Lennard–Jones fluid by molecular dynamics

1986 ◽  
Vol 64 (7) ◽  
pp. 773-781 ◽  
Author(s):  
D. M. Heyes
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Bulk Viscosity ◽  
Shear Viscosity ◽  
Diffusion Coefficients ◽  
Transport Coefficients ◽  
The Self ◽  
Nonequilibrium Molecular Dynamics ◽  
Self Diffusion ◽  
Lennard Jones

New nonequilibrium molecular dynamics (MD) calculations of the shear viscosity, bulk viscosity, and thermal conductivity are presented. Together with the self-diffusion coefficients obtained from equilibrium MD, the success of the Dymond–Batchinski expressions for the density and temperature dependence of these transport coefficients is demonstrated.The shear viscosity and self-diffusion coefficients are very good probes for the approach point of the solid-to-liquid phase change. The bulk viscosity and thermal conductivity are less useful in this respect.

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