We experimentally demonstrate that the coacervation of a biopolymer can trigger a hydrodynamic instability when a coacervate is formed upon injection of a xanthan gum dispersion into a cationic surfactant (C₁₄TAB) solution. The local increase of the viscosity due to the coacervate formation induces a viscous fingering instability. Three characteristic displacement regimes were observed: a viscous fingering dominated regime, a buoyancy-controlled “volcano” regime and a “fan”-like regime determined by the coacervate membrane dynamics. The dependence of the spatial properties of the viscous fingering pattern on the Péclet and Rayleigh numbers is investigated.

中文翻译：

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黄原胶与阳离子表面活性剂凝聚过程中流动驱动的模式形成


我们实验证明，当将黄原胶分散体注入阳离子表面活性剂 （C₁₄TAB） 溶液中时形成凝聚物时，生物聚合物的凝聚会触发流体动力学不稳定。由于凝聚物的形成，粘度的局部增加导致了粘性指法的不稳定性。观察到三种特征性的位移状态：粘性指法主导状态、浮力控制的“火山”状态和由凝聚膜动力学决定的“扇形”状态。研究了粘性指法模式的空间特性对 Péclet 和 Rayleigh 数的依赖性。