发表机构
Indian Institute of Technology Bombay; IIT Guwahati（印度理工学院孟买分校; 印度理工学院古瓦哈提分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过多尺度均匀化方法分析偶应力流体中反应性溶质弥散，发现磁场与浮力分别抑制和增强弥散，并揭示了哈特曼数与偶应力参数的标度关系及壁面吸收的不对称效应。
AI 中文摘要
我们研究了在压力驱动流动、浮力和诱导磁场的联合作用下，偶应力流体在两平行板间流动时反应性溶质的弥散。该模型在通道两壁处纳入一级非均相反应，同时考虑本体反应。利用Mei的多尺度均匀化技术（精确至三阶），我们发展了一种高阶渐近公式，以确定有效纵向弥散系数和浓度场。解析预测辅以布朗动力学模拟和有限差分求解，而Aris矩方法则量化瞬态平均位移、空间方差和有效弥散率。流体动力学分析揭示了当哈特曼数等于偶应力参数一半时速度解出现奇异分支，并确定了哈特曼数与偶应力参数之间的特征四分之一幂标度关系，该关系将偶应力主导区与磁主导区分开。该模型在非反应性牛顿极限下恢复了经典泰勒弥散行为，并与实验测量结果吻合良好。偶应力流变学和磁阻尼抑制了剪切诱导弥散，而浮力通过额外的横向速度梯度增强弥散。随着偶应力参数的增加，弥散系数出现明显的饱和区，而不等壁面吸收导致持续的横向不对称性，更强的吸收增强了源附近的溶质去除。数值和随机结果验证了解析框架，同时解析了高阶浓度结构和粒子尺度壁吸附。
英文摘要
We investigate the dispersion of a reactive solute in a couple-stress fluid flowing between two parallel plates under the combined effects of pressure-driven flow, buoyancy, and an induced magnetic field. The model incorporates first-order heterogeneous reactions at both channel walls alongside a bulk reaction. Using Mei's multiscale homogenization technique accurate to third order, we develop a higher-order asymptotic formulation to determine the effective longitudinal dispersion coefficient and concentration field. Analytical predictions are complemented by Brownian dynamics simulations and finite-difference solutions, while the Aris method of moments quantifies transient mean displacement, spatial variance, and effective dispersivity. The hydrodynamic analysis reveals a singular branch in the velocity solution when the Hartmann number equals half the couple-stress parameter and identifies a characteristic quarter-power scaling between the Hartmann number and couple-stress parameter, separating couple-stress- and magnetically dominated regimes. The model recovers classical Taylor-dispersion behavior in the non-reactive Newtonian limit and agrees well with experimental measurements. Couple-stress rheology and magnetic damping suppress shear-induced dispersion, whereas buoyancy enhances dispersion through additional transverse velocity gradients. A distinct saturation regime of the dispersion coefficient emerges with an increasing couple-stress parameter, while unequal wall absorption induces persistent transverse asymmetry, and stronger absorption enhances solute removal near the source. Numerical and stochastic results validate the analytical framework while resolving higher-order concentration structures and particle-scale wall adsorption.
Comments49 pages, 13 figures
