Transport properties of dense fluids are fundamentally challenging, because the powerful approaches of equilibrium statistical physics cannot be applied. Polar fluids compound this problem, because the long-range interactions preclude the use of a simple effect-diameter approach based solely on hard spheres. Here, we develop a kinetic theory for dipolar hard-sphere fluids that is valid up to high density. We derive a mathematical approximation for the radial distribution function at contact directly from the equation of state, and use it to obtain the shear viscosity. We also perform molecular-dynamics simulations of this system and extract the shear viscosity numerically. The theoretical results compare favorably to the simulations.
Kinetic Theory for the Shear Viscosity of Dense Binary Dipolar Fluid Mixtures
Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology（挪威科技大学机械与工业工程系）；Instituto de Alta Investigación, Universidad de Tarapacá（塔拉帕卡大学高等研究所）
The shear viscosity for a moderately dense granular binary mixture of smooth hard spheres undergoing uniform shear flow is determined. The basis for the analysis is the Enskog kinetic equation, solved first analytically by the Chapman-Enskog method up to first order in the shear rate for unforced systems as well as for systems driven by a Gaussian thermostat. As in the elastic case, practical evaluation requires a Sonine polynomial approximation. In the leading order, we determine the shear viscosity in terms of the control parameters of the problem: solid fraction, composition, mass ratio, si…
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The paper is devoted to a detailed analysis of the two important transport processes - the kinematic shear viscosity and the self-diffusion - for all states of liquid water from the triple point to the critical point. Our approach to the shear viscosity is grounded on friction effects between the two nearest molecular layers shifting relative to each other. In this relation, the nature of the shear viscosity in water is fully similar to that in argon. The contribution, caused by interlayer displacements of molecules, is assumed to be negligibly small. The behavior of the kinematic shear viscos…
We present molecular dynamics simulations of pseudo hard sphere fluid (generalized WCA potential with exponents (50, 49) proposed by Jover et al. J. Chem. Phys 137, (2012)) using GROMACS package. The equation of state and radial distribution functions at contact are obtained from simulations and compared to the available theory of true hard spheres (HS) and available data on pseudo hard spheres. The comparison shows agreements with data by Jover et al. and the Carnahan-Starling equation of HS. The shear viscosity is obtained from the simulations and compared to the Enskog expression and previo…
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