An extended analysis of the viscosity kernel for monatomic and diatomic fluids

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Title: An extended analysis of the viscosity kernel for monatomic and diatomic fluids
Author(s): Puscasu, R. M.; Todd, B. D.; Daivis, P. J.; Hansen, J. S.
Abstract: We present an extended analysis of the wavevector dependent shear viscosity of monatomic and diatomic (liquid chlorine) fluids over a wide range of wavevectors and for a variety of state points. The analysis is based on equilibrium molecular dynamics simulations, which involve the evaluation of transverse momentum density and shear stress autocorrelation functions. For liquid chlorine we present the results in both atomic and molecular formalisms. We find that the viscosity kernel of chlorine in the atomic representation is statistically indistinguishable from that in the molecular representation. The results further suggest that the real space viscosity kernels of monatomic and diatomic fluids depend sensitively on the density, the potential energy function and the choice of fitting function in reciprocal space. It is also shown that the reciprocal space shear viscosity data can be fitted to two different simple functional forms over the entire density, temperature and wavevector range: a function composed of n-Gaussian terms and a Lorentzian-type function. Overall, the real space viscosity kernel has a width of 3-6 atomic diameters, which means that the generalized hydrodynamic constitutive relation is required for fluids with strain rates that vary nonlinearly over distances of the order of atomic dimensions.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Molecular Simulation
Source: Journal of Physics: Condensed Matter, Vol. 22, no. 19 (May 2010)
Publication year: 2010
FOR Code(s): 0204 Condensed Matter Physics; 0206 Quantum Physics; 1007 Nanotechnology
Keyword(s): Diatomic fluids; Monoatomic fluids; Viscosity kernels
Publisher: Institute of Physics Publishing
ISSN: 0953-8984
Publisher URL: http://dx.doi.org/10.1088/0953-8984/22/19/195105
Peer reviewed