Constitutive modeling of dilute wormlike micelle solutions: Shear-induced structure and transient dynamics
Constitutive modeling of dilute wormlike micelle solutions: Shear-induced structure and transient dynamics
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DOI：
10.1016/j.jnnfm.2021.104606
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发表时间：
2021-07-13
影响因子：
3.1
通讯作者：
Graham, Michael D.
中科院分区：
文献类型：
--
作者：
Hommel, Richard J.;Graham, Michael D.
我们提出了Dutta和Graham（2018）的“反应棒模型”（RRM）的重新表述，该模型是描述稀释虫状胶束溶液行为的本构模型。RRM将蠕虫状胶束溶液视为刚性布朗棒的稀悬浮液，在流动中经历可逆的断裂和生长。胶束取向和应力贡献的演化方程与集体胶束长度的动力学反应方程耦合，产生棒的长度和旋转扩散率的动态变化。该模型已经成功地捕获了稀蠕虫状胶束溶液的许多关键稳态流变特性，特别是剪切增厚和变薄、非零法向应力差和可重入剪切应力-剪切速率曲线，并且可以拟合各种稳态实验数据。通过在更微观的结构（尽管仍然高度理想化）的基础上重新制定胶束生长的动力学方程，目前的工作改进了这个框架，该框架难以捕捉瞬态动力学和高剪切行为。特别是，我们允许胶束生长与棒的强对齐和由于沿胶束的拉伸应力而导致的断裂有关。这个新公式捕获了稳态和瞬态剪切流变，与实验结果很好地吻合。我们也发现与现有的稳态拉伸流变学有很好的一致性。
We present a reformulation of the 'reactive rod model' (RRM) of Dutta and Graham (2018), a constitutive model for describing the behavior of dilute wormlike micelle solutions. The RRM treats wormlike micelle solutions as dilute suspensions of rigid Brownian rods undergoing reversible scission and growth in flow. Evolution equations for micelle orientation and stress contribution are coupled to a kinetic reaction equation for a collective micelle length, producing dynamic variations in the length and rotational diffusivity of the rods. This model has previously shown success in capturing many critical steady-state rheological features of dilute wormlike micelle solutions, particularly shear-thickening and -thinning, non-zero normal stress differences, and a reentrant shear stress-shear rate curve, and could fit a variety of steady state experimental data. The present work improves on this framework, which showed difficulty in capturing transient dynamics and high-shear behavior, by reformulating the kinetic equation for micelle growth on a more microstructural (though still highly idealized) basis. In particular, we allow for micelle growth associated with strong alignment of rods and breakage due to tensile stresses along the micelles. This new formulation captures both steady and transient shear rheology in good agreement with experiments. We also find good agreement with available steady state extensional rheology.