发表机构
University of British Columbia; University of Cambridge（不列颠哥伦比亚大学; 剑桥大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究弹粘塑性圆形库埃特流，发现含低剪切速率区域的连续应力基态在零雷诺数下线性不稳定，经数值模拟揭示其非线性动力学及聚合物应力扩散的作用。
AI 中文摘要
本文对由Saramito（宾汉）本构定律描述的弹粘塑性流体的二维圆形库埃特流展开研究，构建了轴对称基态。如先前研究所述，这类基态并非唯一，任何塞流区域的应力取决于初始聚合物应力，且剪切速率与应力可在屈服面处发生不连续跳跃。研究表明，当基态包含相对低剪切速率区域时，具有连续应力分布的基态在雷诺数为零时呈线性不稳定；随方位波数增大，不稳定模式增强并局域于屈服面。通过数值模拟探究该不稳定性的非线性动力学，线性不稳定模式饱和至有限振幅后形成时空复杂态；引入聚合物应力扩散以简化数值模拟，消除了最短波长处的正应力不连续性与不稳定性。研究发现，只要基流包含相对低剪切速率区域，就会发生不稳定性并向复杂动力学转变。
英文摘要
An exploration is presented of two-dimensional, circular Couette flow of an elasto-viscoplastic fluid described by Saramito's (Bingham) constitutive law. Axisymmetrical base states are constructed. As has been noted previously, such states are not unique, with stresses over any plugs depending on the initial polymer stress, and the shear rate and stress may jump discontinuously across the yield surfaces. We show that base states with continuous stress profiles are linearly unstable at zero Reynolds number when they contain regions with relatively low shear rate. Unstable modes become stronger and localized to the yield surfaces as the azimuthal wavenumber increases. We report numerical simulations exploring the nonlinear dynamics of the instability. The linear unstable modes saturate at finite amplitude to create spatio-temporally complicated states. Polymer stress diffusion is added to ease these numerical simulations, eliminating normal-stress discontinuities and instability at the shortest wavelengths. Instability and transition to complex dynamics occur whenever the base flow contains regions with relatively low shear rate.
Comments34 pages, 18 figures
