Inspired by the problem of the removal of in situ gel-like materials via a displacement flow process, we use a fluidic device known as Hele-Shaw cell to study the flow parameters related to the displacement flow efficiency. In a displacement flow process, when a less viscous fluid displaces a more viscous fluid, exotic interfacial patterns known as viscous fingering appear. Motivated by the recent developments in the literature, we experimentally study the effects of a simple cell nonuniformity with various gap gradients in the flow passage on the viscous fingering problem in the displacement of a viscoplastic gel (Carbopol) by air. We show that a linearly converging/diverging cell can be used to control certain interfacial patterns and improve the displacement efficiency. We classify the flow regimes into smooth finger and rough finger patterns, using the average capillary number (Ca) and the average Bingham number (Bn) or their combinations.

中文翻译：

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非均匀Hele-Shaw单元中的多相粘塑性流：控制界面模式的流体装置。

受到通过置换流动过程去除原位凝胶状材料的问题的启发，我们使用一种称为Hele-Shaw细胞的流体装置来研究与置换流动效率相关的流动参数。在置换流动过程中，当较低粘度的流体置换较高粘度的流体时，会出现称为粘性指状的奇异界面模式。受文献的最新发展的启发，我们实验研究了在流动通道中具有各种间隙梯度的简单细胞不均匀性对空气中粘塑性凝胶（Carbopol）的粘性指法问题的影响。我们表明，线性收敛/发散单元可用于控制某些界面模式并提高置换效率。我们将流态分类为使用平均毛细血管数（C a）和平均宾厄姆数（B n）或它们的组合，使手指和手指形状变得平滑。