Centre for Molecular Simulation, Swinburne University of Technology, Hawthorn, Victoria, Australia.
J Phys Condens Matter. 2010 May 19;22(19):195105. doi: 10.1088/0953-8984/22/19/195105. Epub 2010 Apr 16.
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.
我们对单原子（液态氯）和双原子（液态氯）流体在宽波矢范围和多种状态点下的波矢相关剪切黏度进行了扩展分析。该分析基于平衡分子动力学模拟，涉及横向动量密度和剪切应力自相关函数的评估。对于液态氯，我们以原子和分子两种形式呈现了结果。我们发现，原子表示中的氯黏度核在统计学上与分子表示中的黏度核无法区分。结果进一步表明，单原子和双原子流体的实空间黏度核强烈依赖于密度、位能函数和倒空间拟合函数的选择。还表明，在整个密度、温度和波矢范围内，倒空间剪切黏度数据可以拟合到两种不同的简单函数形式：由 n-高斯项组成的函数和洛伦兹型函数。总体而言，实空间黏度核的宽度为 3-6 个原子直径，这意味着对于应变率在原子尺寸量级的距离上呈非线性变化的流体，需要广义流体动力学本构关系。
