Physics Division, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan.
Shull Wollan Center, University of Tennessee and Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev E. 2018 Jan;97(1-1):012605. doi: 10.1103/PhysRevE.97.012605.
The molecular rearrangements of most fluids under flow and deformation do not directly follow the macroscopic strain field. In this work, we describe a phenomenological method for characterizing such nonaffine deformation via the anisotropic pair distribution function (PDF). We demonstrate how the microscopic strain can be calculated in both simple shear and uniaxial extension, by perturbation expansion of anisotropic PDF in terms of real spherical harmonics. Our results, given in the real as well as the reciprocal space, can be applied in spectrum analysis of small-angle scattering experiments and nonequilibrium molecular dynamics simulations of soft matter under flow.
大多数流体在流动和变形下的分子重排并不直接遵循宏观应变场。在这项工作中，我们通过各向异性的对分布函数（PDF）描述了一种描述这种非仿射变形的唯象方法。我们通过用实球谐函数展开各向异性 PDF 的微扰展开，展示了如何在简单剪切和单轴拉伸中计算微观应变。我们的结果以实空间和倒易空间给出，可应用于小角散射实验的谱分析和流动下软物质的非平衡分子动力学模拟。
