Interfacial effects on droplet dynamics in Poiseuille flow
Interfacial effects on droplet dynamics in Poiseuille flow
复制标题
泊肃叶流中液滴动力学的界面效应
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
P. G. D. Sastre
中科院分区：
文献类型：
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作者：
M. Charco;P. G. D. Sastre
乳液的许多特性源于界面流变学，但缺乏对界面粘度对液滴动力学影响的理论理解。在这里，我们报告了这样一个理论，与泊肃叶流中的孤立球形液滴有关。斯托克斯流假设为体相，界面处水动力应力的跳跃根据 Boussinesq-Scriven 本构定律由 Marangoni 和表面粘性力平衡。我们的模型采用表面活性剂的线性状态方程。我们的分析预测了滑移、跨流迁移和液滴循环速度。这些结果和相应的界面参数是可分离的：例如，仅当存在表面活性剂浓度梯度时才会发生跨流迁移；滑移速度取决于粘度对比和膨胀特性，但不取决于剪切布辛斯克数。这种可分离性提供了一种新的、有利的方法来直接从液滴界面测量表面粘性力和弹力。
Many properties of emulsions arise from interfacial rheology, but a theoretical understanding of the effect of interfacial viscosities on droplet dynamics is lacking. Here we report such a theory, relating to isolated spherical drops in a Poiseuille flow. Stokes flow is assumed in the bulk phases, and a jump in hydrodynamic stress at the interface is balanced by Marangoni and surface viscous forces according to the Boussinesq–Scriven constitutive law. Our model employs a linear equation of state for the surfactant. Our analysis predicts slip, cross-stream migration and droplet-circulation velocities. These results and the corresponding interfacial parameters are separable: e.g., cross-stream migration occurs only if gradients in surfactant concentration are present; slip velocity depends on viscosity contrast and dilatational properties, but not on shear Boussinesq number. This separability allows a new and advantageous means to measure surface viscous and elastic forces directly from the drop interface.