Xu Peng, Cagin Tahir, Goddard William A
Materials and Process Simulation Center (I39-74), California Institute of Technology, Pasadena, 91125, USA.
J Chem Phys. 2005 Sep 8;123(10):104506. doi: 10.1063/1.1881052.
The shear viscosity of liquid copper is studied using nonequilibrium molecular-dynamics simulations under planar shear flow conditions. We examined variation of viscosity as function of shear rate at a range of pressures (ca. 0 - 40 GPa). We analyzed these results using eight different phenomenological models and find that the observed non-Newtonian behavior is best described by the Powell-Eyring (PE) model: eta(gamma) = (eta(0)-eta(infinity))sinh(-1)(taugamma)(taugamma) + eta(infinity), where gamma is the shear rate. Here eta(0) (the zero-shear-rate viscosity) extracted from the PE fit is in excellent agreement with available experimental data. The relaxation time tau from the PE fit describes the shear response to an applied stress. This provides the framework for interpreting the shear flow phenomena in complex systems, such as liquid metal and amorphous metal alloys.
在平面剪切流条件下，利用非平衡分子动力学模拟研究了液态铜的剪切粘度。我们在一系列压力（约0 - 40 GPa）下，考察了粘度随剪切速率的变化。我们使用八种不同的唯象模型分析了这些结果，发现观察到的非牛顿行为最好用鲍威尔 - 艾林（PE）模型来描述：η(γ) = (η(0) - η(∞)) sinh⁻¹(τγ)/(τγ) + η(∞)，其中γ是剪切速率。从PE拟合中提取的η(0)（零剪切速率粘度）与现有实验数据高度吻合。PE拟合得到的弛豫时间τ描述了对应力施加的剪切响应。这为解释复杂系统（如液态金属和非晶态金属合金）中的剪切流动现象提供了框架。
