Abstract We study the flow behaviors of emulsion droplets in constricted capillaries using a surfactant Lattice Boltzmann model. We first establish the model by introducing a surfactant component into the pseudopotential multiphase model and characterizing the amphiphilic structure using dipoles. Then we study the flow of emulsion droplets in single or parallel capillaries. The simulations show that single droplet can pass through single throat in three ways, i.e., passing directly, passing with deformation, and snap-off. Multiple droplets may flow through the capillary with coalescence, and can also block the throat by adsorption or bridging, which may induce upstream flow caused by buoyancy. There is a “trap effect” when emulsions flow through parallel throats, and the droplet could be pinched off by obstacles, while the surfactants can inhibit the droplet breakup due to Marangoni effect. The simulations present detailed flow behaviors at pore scale and provide new insights for emulsion flow modeling.

中文翻译：

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收缩毛细管中乳液的流动行为：格子玻尔兹曼模拟研究

摘要 我们使用表面活性剂格子玻尔兹曼模型研究了收缩毛细管中乳液液滴的流动行为。我们首先通过将表面活性剂成分引入赝势多相模型并使用偶极子表征两亲结构来建立模型。然后我们研究乳液液滴在单个或平行毛细管中的流动。模拟表明，单个液滴可以通过三种方式通过单个喉部，即直接通过、变形通过和折断。多个液滴可以通过聚结流过毛细管，也可以通过吸附或架桥堵塞喉部，这可能会引起浮力引起的上游流动。当乳液流过平行的喉道时会产生“陷阱效应”，液滴可能会被障碍物夹住，而表面活性剂可以抑制由于马兰戈尼效应引起的液滴破裂。模拟展示了孔隙尺度上的详细流动行为，并为乳液流动建模提供了新的见解。