发表机构
Université de Montpellier（蒙彼利埃大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过二维高斯Rouse链模型，发现仅分块摩擦异质性即可在Batchelor-Kraichnan随机流中重新分布聚合物变形，高摩擦块更伸展，且效应不依赖全局弛豫时间尺度。
AI 中文摘要
我们研究了一个二维高斯Rouse链，该链被划分为两个相邻的块，具有不同的局部摩擦系数但具有相同的Hookean弹性。在静止条件下，摩擦异质性不改变连续时间平衡高斯构象，但产生不同的块迁移率和修改的广义弛豫谱。精确的摩擦加权平动扩散系数保持标度$D_\gamma\propto N^{-1}$，并带有依赖于摩擦的前因子；相应的扩散定律和广义模式公式可推广到更一般的局部摩擦分布。然后我们将链置于不可压缩的Batchelor-Kraichnan随机流中。在共同的外部流动下，高摩擦块比低摩擦块更伸展。变形不对称性随摩擦对比度增强而增强，并在弱至中等流动区域发展，在最强有限时间条件下仍清晰可见。当链特定的最长模式Weissenberg数在不同摩擦比下匹配时，这种不对称性仍然存在，表明在相同的有限时间协议内，该效应不能仅由全局弛豫时间尺度的移动来解释。在广义模式坐标中，平滑随机应变不直接混合模式指数，并优先放大最慢模式。在更大的流动强度下，延伸分布显著变宽，并在模拟时间窗口内表现出明显的时域漂移。由于所有模拟的链特定最长模式Weissenberg数均低于1，这种漂移被解释为向线圈-拉伸阈值附近具有宽幂律尾部的静止Hookean态的缓慢收敛。总体而言，仅摩擦异质性就足以在原本机械均匀的聚合物上重新分布变形。
英文摘要
We study a two-dimensional Gaussian Rouse chain divided into two contiguous blocks with different local friction coefficients but identical Hookean elasticity. In quiescent conditions, friction heterogeneity leaves the continuous-time equilibrium Gaussian conformation unchanged while producing distinct block mobilities and a modified generalized relaxation spectrum. The exact friction-weighted translational diffusion coefficient retains the scaling $D_γ\propto N^{-1}$, with a friction-dependent prefactor; the corresponding diffusion law and generalized-mode formulation extend beyond the diblock to more general local friction profiles. We then place the chain in an incompressible Batchelor-Kraichnan random flow. Under a common external flow, the high-friction block becomes more extended than the low-friction block. The deformation asymmetry strengthens with friction contrast and develops across the weak- to moderate-flow regime, remaining clearly visible at the strongest finite-time conditions. It also persists when the chain-specific longest-mode Weissenberg number is matched across friction ratios, showing that, within the same finite-time protocol, the effect is not accounted for solely by a shift of the global relaxation timescale. In generalized-mode coordinates, the smooth random strain does not directly mix mode indices and preferentially amplifies the slowest mode. At larger flow strengths, extension distributions broaden markedly and exhibit pronounced temporal drift over the simulated time window. Since all simulated chain-specific longest-mode Weissenberg numbers remain below unity, this drift is interpreted as slow convergence toward the broad, power-law-tailed stationary Hookean regime near the coil-stretch threshold. Overall, friction heterogeneity alone is sufficient to redistribute deformation along an otherwise mechanically uniform polymer.
Comments22 pages, 6 figures. Simulation code and data are available at Zenodo: https://doi.org/10.5281/zenodo.22857749
