发表机构
Physics Department, Emory University（埃默里大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究比较了三种粒子尺度重排度量，推荐了适用于高多分散系统的邻域定义方法，并揭示了邻域选择对$D^2_{\min}$结果的影响。
AI 中文摘要
我们比较了在高多分散材料受驱动流动中三种粒子尺度的重排度量：（a）相对于时间平均平均流定义的非仿射运动，（b）最近邻连接性的变化，以及（c）$D^2_{\min}$，它测量相对于在空间和时间上局部拟合的仿射变形的非仿射运动[Falk and Langer, Phys. Rev. E 57, 7192 (1998)]。我们将这些度量应用于先前发表的二维模拟[Jiang, Sussman, and Weeks, Phys. Rev. E 108, 054605 (2023)]和颗粒流实验[Illing and Weeks, Phys. Rev. E 111, 045422 (2025)]，其多分散性高达$\delta\approx0.50$。连接性的变化和$D^2_{\min}$都需要定义邻近粒子，这使得在高多分散系统中邻域的选择变得非平凡。为了检测连接性的变化，我们推荐使用激进Delaunay三角剖分，它提供了一种尺寸感知的拓扑邻居定义。为了计算$D^2_{\min}$，我们推荐使用尺寸感知的成对截断距离方法。我们进一步表明，改变邻域定义可以逆转实验数据中$D^2_{\min}$对粒子尺寸的表观依赖性。因此，$D^2_{\min}$的趋势不能独立于用于计算它的邻域来解释。总的来说，所提出的三种度量提供了关于高多分散系统中重排的互补信息。
英文摘要
We compare three particle-scale measures of rearrangement in highly polydisperse materials under driven flow: (a) nonaffine motion defined relative to the time-averaged mean flow, (b) changes in nearest-neighbor connectivity, and (c) $D^2_{\min}$, which measures nonaffine motion relative to an affine deformation fitted locally in space and time [Falk and Langer, Phys. Rev. E 57, 7192 (1998)]. We apply these measures to previously published two-dimensional simulations [Jiang, Sussman, and Weeks, Phys. Rev. E 108, 054605 (2023)] and granular-flow experiments [Illing and Weeks, Phys. Rev. E 111, 045422 (2025)] with polydispersities up to $δ\approx0.50$. Changes in connectivity and $D^2_{\min}$ both require a definition of neighboring particles, making the choice of neighborhood nontrivial in highly polydisperse systems. For detecting changes in connectivity, we recommend radical Delaunay triangulation, which provides a size-aware topological definition of neighbors. For calculating $D^2_{\min}$, we recommend a size-aware pairwise cutoff distance method. We further show that changing the neighborhood definition can reverse the apparent dependence of $D^2_{\min}$ on particle size in experimental data. Thus, trends in $D^2_{\min}$ cannot be interpreted independently of the neighborhood used to calculate it. Overall, the three measures presented provide complementary information about rearrangements in highly polydisperse systems.
CommentsWhen particles come in every size, even deciding who counts as a neighbor can turn the story upside down. We show how that simple choice changes what you see when a material rearranges
