Nonlinear-Flow-Induced Structure in Fiber Suspensions

abstractcts - 9910908 d。纤维悬浮液、晶体聚合物等复杂流体的流变行为在造纸、食品和制药工业中具有重要意义。对于许多这样的流存在线性解，但对于许多应用，非线性项变得重要并且必须包括在内。本文提出在粘弹性、流体惯性、电双层相互作用和纤维-纤维粘附四种情况下研究三种非线性：1)振荡线性流动不显示从一个周期到下一个周期的任何方向变化：然而，当非线性项出现时，方向的累积漂移。这三种情况下，将研究宽范围的幅度和频率。ii)考虑纤维长度（高雷诺数）时，纤维悬浮在流体中的情况强调惯性力，但当纤维直径为相关尺寸（雷诺数接近于1）时，粘性效应可能占主导地位。将发展细长体理论，并将其应用于库埃特流中单个旋转纤维的情况。iii)带电杆预计会与带相反电荷的离子相互作用，从而对杆的取向产生影响。计划进行实验来检验PI早期关于电粘性效应的理论工作。iv)稠密的悬浮液将粘性效应（流体-体表面相互作用）和哥伦比亚摩擦定律（体-体接触）结合在一起。这种相互作用的研究将特别关注粘接纤维与纤维的接触。

AbstractCTS-9910908D. L. Koch, Cornell UniversityThe rheological behavior of such complex fluids as fiber suspensions, crystal polymers, etc. are important in the paper, food, and pharmaceutical industries. Linear solutions exist for a number of these flows, but for many applications, nonlinear terms become important and must be included. It is proposed to study thee nonlinearities in the context of four situations highlighting viscoelasticity, fluid inertia, electrical double layer interactions, and fiber-fiber adhesion:i) Oscillatory linear flows do not show any change of orientation from one cycle to the next: there is, however, a cumulative drift of orientation when non-linear terms appear. Three such cases will be studied for a wide range of amplitude and frequency.ii) The case of fibers suspended in fluids emphasizes the inertia forces when considering their length (high Reynolds numbers), but viscous effects may dominate when the fiber diameter is the relevant dimension (Reynolds numbers near unity). A slender body theory will be developed and applied to the case of a single rotating fiber in a Couette flow.iii) Electrically charged rods are expected to interact with ions of opposite charge, with their resulting effect on the rod orientation. Experiments are planned to test the PI's earlier theoretical work on electoviscous effects.iv) Dense suspensions bring together viscous effects (fluid-body surface interaction) and Columbic friction laws (body-body contact). Such interactions will be studied with special attention to adhesive fiber-fiber contact.