Fabian Hillebrand, Stylianos Varchanis, Cameron C. Hopkins, Simon J. Haward and Amy Q. Shen
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引用次数: 0
摘要
我们结合数值模拟和实验验证,对剪切带粘弹性蠕虫状胶束(WLM)溶液在不同深度(D)和长度(L)的凹面上的蠕变流动行为进行了全面研究。流体采用扩散吉塞克斯模型建模,模型参数设置为定量描述用于实验验证的 100 : 60 mM 氯化十六烷基吡啶鎓:水杨酸钠 WLM 水溶液的剪切流变学。当长度 L 超过深度 D 和通道宽度 W 之和时,我们观察到 "空腔流 "向 "膨胀-收缩流 "的过渡。当 L≤D + W 时,"空腔流 "的特征是跨越凹面长度的大尺度再循环。当 L > D + W 时,在 "膨胀-收缩流 "中观察到的再循环仅限于膨胀平面下游和收缩平面上游的显著角落。利用数值数据集,我们构建了不同固定韦森伯格数 Wi 下的 L-D 相图,描述了受粘弹性效应影响的涡旋结构的转变和演变。
Flow of wormlike micellar solutions over concavities†
We present a comprehensive investigation combining numerical simulations with experimental validation, focusing on the creeping flow behavior of a shear-banding, viscoelastic wormlike micellar (WLM) solution over concavities with various depths (D) and lengths (L). The fluid is modeled using the diffusive Giesekus model, with model parameters set to quantitatively describe the shear rheology of a 100 : 60 mM cetylpyridinium chloride:sodium salicylate aqueous WLM solution used for the experimental validation. We observe a transition from “cavity flow” to “expansion–contraction flow” as the length L exceeds the sum of depth D and channel width W. This transition is manifested by a change of vortical structures within the concavity. For L ≤ D + W, “cavity flow” is characterized by large scale recirculations spanning the concavity length. For L > D + W, the recirculations observed in “expansion–contraction flow” are confined to the salient corners downstream of the expansion plane and upstream of the contraction plane. Using the numerical dataset, we construct phase diagrams in L–D at various fixed Weissenberg numbers Wi, characterizing the transitions and describing the evolution of vortical structures influenced by viscoelastic effects.