Nonequilibrium equation of state for Lennard‐Jones fluids and the calculation of strain‐rate dependent shear viscosity

Ahmed, Alauddin; Sadus, Richard J.

doi:10.1002/aic.12257

Cited by 5 publications

(13 citation statements)

References 27 publications

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“…8. The literature data on η from Heyes 18 and Ahmed and Sadus 16 agree very well with the correlations over the whole range of thermodynamic states that was considered in the present work. They scatter mainly within a band of ±10%.…”

Section: E Comparison Of the Correlations With Literature Datasupporting

confidence: 86%

“…For each state point, five different shear rateṡ γ ∈ [0.1, 1.0] were studied. Literature data for a comparison are only available for η and D. [16][17][18] Where comparisons are possible, the present results agree with those from the literature.…”

Section: Introductionsupporting

confidence: 87%

“…Hence, for a comparison, only MD data on LJ-type fluids from the literature were used. [16][17][18] These data are compared here to the correlations that were obtained in the present work using the simulation data for the LJTS fluid. It is known from a previous study of our group 8 that the truncation and shifting of the LJ potential has only little influence on the viscosity as long as the thermodynamic state is not too close to the critical point.…”

Section: E Comparison Of the Correlations With Literature Datamentioning

confidence: 81%

“…Only a few studies report data for a wide range of thermodynamic states and for the LJT fluid only. There, the shear-rate dependence of the pressure, internal energy, and shear viscosity [16][17][18] as well as the self-diffusion coefficient 17,18 was investigated. But very little is known on the shear-rate dependence of other properties.…”

Section: Introductionmentioning

confidence: 99%

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Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

Lautenschlaeger

Hasse

2019

Physics of Fluids

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It was shown recently that using the two-gradient method, thermal, caloric, and transport properties of fluids under quasi-equilibrium conditions can be determined simultaneously from nonequilibrium molecular dynamics simulations. It is shown here that the influence of shear stresses on these properties can also be studied using the same method. The studied fluid is described by the Lennard-Jones truncated and shifted potential with the cut-off radius r * c = 2.5σ. For a given temperature T and density ρ, the influence of the shear rate on the following fluid properties is determined: pressure p, internal energy u, enthalpy h, isobaric heat capacity cp, thermal expansion coefficient αp, shear viscosity η, and self-diffusion coefficient D. Data for 27 state points in the range of T ∈ [0.7, 8.0] and ρ ∈ [0.3, 1.0] are reported for five different shear rates (γ ∈ [0.1, 1.0]). Correlations for all properties are provided and compared with literature data. An influence of the shear stress on the fluid properties was found only for states with low temperature and high density. The shear-rate dependence is caused by changes in the local structure of the fluid which were also investigated in the present work. A criterion for identifying the regions in which a given shear stress has an influence on the fluid properties was developed. It is based on information on the local structure of the fluid. For the self-diffusivity, shear-induced anisotropic effects were observed and are discussed.

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Section: E Comparison Of the Correlations With Literature Datasupporting

confidence: 86%

Section: Introductionsupporting

confidence: 87%

Section: E Comparison Of the Correlations With Literature Datamentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

Lautenschlaeger

Hasse

2019

Physics of Fluids

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“…Vrabec and collaborators [19,20] have used site-site LJ potentials to correlate the thermophysical properties, including viscosity, of cyclic alkanes and small molecules. Numerous authors have used the effective spherical LJ 12-6 potential to investigate the viscosity of real and ideal fluids by means of molecular simulations [21][22][23][24][25][26][27][28]. The preponderance of the LJ 12-6 potential in MD simulations gives the current work a more general context of testing its limitations, albeit only in the dilute gas limit, where a combination of the kinetic theory and classical trajectory calculations provide us with an accurate method of calculating the viscosity.…”

Section: 0%mentioning

confidence: 99%

Dilute gas viscosity ofn-alkanes represented by rigid Lennard-Jones chains

2016

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The shear viscosity in the dilute gas limit has been calculated by means of the classical trajectory method for a gas consisting of chain-like molecules. The molecules were modelled as rigid chains made up of spherical segments that interact through a combination of site-site Lennard-Jones 12-6 potentials. Results are reported for chains consisting of 2, 3, 4, 6, 8, 12 and 16 segments in the reduced temperature range of 0.3 – 50 for site-site separations of 0.25 , 0.333 , 0.40 , 0.60 and 0.80 , where is the Lennard-Jones length scaling parameter. The results were used to determine the shear viscosity of n-alkanes in the zerodensity limit by representing an n-alkane molecule as a rigid linear chain consisting of c − 1 spherical segments, where c is the number of carbon atoms. We show that for a given n-alkane molecule, the scaling parameters ε and σ are not unique and not transferable from one molecule to another. The commonly used site-site Lennard-Jones 12-6 potential in combination with a rigid-chain molecular representation can only accurately mimic the viscosity if the scaling parameters are fitted. If the scaling parameters are estimated from the scaling parameters of other n-alkanes, the predicted viscosity values have an unacceptably high uncertainty

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A Laplacian-based algorithm for non-isothermal atomistic-continuum hybrid simulation of micro and nano-flows

Alexiadis¹,

Lockerby²,

Borg³

et al. 2013

Computer Methods in Applied Mechanics and Engineering

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We propose a new hybrid algorithm for incompressible micro and nanoflows that applies to non-isothermal steady-state flows and does not require the calculation of the Irving–Kirkwood stress tensor or heat flux vector. The method is validated by simulating the flow in a channel under the effect of a gravity-like force with bounding walls at two different temperatures and velocities. The model shows very accurate results compared to benchmark full MD simulations. In the temperature results, in particular, the contribution of viscous dissipation is correctly evaluated

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Nonequilibrium equation of state for Lennard‐Jones fluids and the calculation of strain‐rate dependent shear viscosity

Cited by 5 publications

References 27 publications

Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

Dilute gas viscosity ofn-alkanes represented by rigid Lennard-Jones chains

A Laplacian-based algorithm for non-isothermal atomistic-continuum hybrid simulation of micro and nano-flows

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