聚合物流动中轴向分散的控制：磁效应与电渗效应的对比
Control of axial dispersion in polymeric flows: magnetic effect versus electroosmotic effect
- Harbin Institute of Technology（哈尔滨工业大学）
- City University of Hong Kong（香港城市大学）
- National University of Singapore（新加坡国立大学）
- Shandong University（山东大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过解析和广义分散模型，对比磁效应与电渗效应，揭示聚合物微管流中轴向分散的控制机制，识别三种流动状态并发现非单调临界响应，为微流体混合分离提供新范式。
AI中文摘要：
自Taylor关于可溶物质分散的开创性工作以来，溶质分散的建模与控制一直受到广泛关注。本研究探讨了在微管内由非稳态磁流体动力学-振荡电渗流驱动的聚合物溶液中的溶质分散，旨在通过微尺度流动揭示复杂流变介质中的输运机制。首先，基于Debye-Hückel近似，严格推导了混合磁流体动力学-电流体动力学流动的电位和速度分布的解析解。随后，利用Sankarasubramanian & Gill的广义分散模型，建立了数学模型以系统研究水动力分散的时间演化。通过研究电动场和磁场的协同调制，我们识别出三种不同的流动状态，即电场主导、竞争过渡和磁场限制状态，并定量定义了它们随振荡雷诺数$Re$和Deborah数$De$变化的边界及演化，从而实现了精确的流动状态分类。此外，在广泛的振荡雷诺数范围内观察到控制溶质分散的非单调临界响应，这为微流体混合与分离提供了新的控制范式。进一步地，通过对分数阶Maxwell、经典Maxwell和Newtonian流体的比较分析，我们表明微观结构松弛在多场耦合下的宏观溶质输运中起着关键作用。我们的发现有助于揭示电磁耦合系统中精确质量输运控制的流动机制，推动微流体装置和生物医学检测技术的发展。
英文摘要：
Since Taylor's seminal work on the dispersion of soluble matter, the modeling and control of solute dispersion have received considerable attention. This study investigates the solute dispersion in polymer solutions driven by unsteady magnetohydrodynamic-oscillatory electroosmotic flow within a microtube, aiming to reveal the transport mechanisms in complex rheological media through microscale flow. Firstly, based on the Debye-Hückel approximation, analytical solutions for the electric potential and velocity distributions of mixed magnetohydrodynamic-electrohydrodynamic flows are rigorously derived. Subsequently, using Sankarasubramanian \& Gill's generalized dispersion model, mathematical models are developed to systematically investigate the temporal evolution of hydrodynamic dispersion. By investigating the synergistic modulation of electrokinetic and magnetic fields, we identify three distinct flow regimes, namely the electric-field-dominant, competitive transition, and magnetic-field-limited regimes, and quantitatively define their boundaries and evolution with oscillatory Reynolds number $Re$ and Deborah number $De$, thus allowing accurate flow regime classification. Moreover, a non-monotonic critical response governing solute dispersion is observed over a wide range of oscillatory Reynolds numbers, which provides a novel control paradigm for microfluidic mixing and separation. Additionally, through a comparative analysis of fractional Maxwell, classical Maxwell, and Newtonian fluids, we show that microscopic structural relaxation plays a crucial role in macroscopic solute transport under multi-field coupling. Our findings help to reveal flow mechanisms for precise mass transport control in electro-magnetically coupled systems, advancing the development of microfluidic devices and biomedical detection technologies.
