该研究小组利用微流控装置研究了不互溶驱替,该装置具有精确控制的结构化表面,类似于模拟粗糙裂缝。研究人员分析了表面粗糙度对浸润相变和保护液体薄膜形成的影响。他们通过实验证明并从理论上解释,粗糙度对薄膜的稳定性和去润湿动力学产生影响,从而导致未被驱替的流体在后期呈现出不同的形态。最后,研究人员讨论了这些观察结果对地质和技术应用的影响。
据介绍,在受限几何结构中的不互溶流体-流体驱替是许多自然现象和技术应用中的基本过程,例如地质二氧化碳封存和微流体学。由于流体与固体壁之间的相互作用,流体入侵过程经历了从低驱替速率下的完全驱替到高驱替速率下在受限表面上形成保护液体薄膜的浸润相变。尽管大多数表面都存在粗糙度,但受限和粗糙几何形态中可能出现的流体-流体驱替类型仍然存在基本问题。
附:英文原文
Title: Wetting transition and fluid trapping in a microfluidic fracture
Author: Qiu, Yu, Xu, Ke, Pahlavan, Amir A., Juanes, Ruben
Issue&Volume: 2023-5-22
Abstract: Immiscible fluid–fluid displacement in confined geometries is a fundamental process occurring in many natural phenomena and technological applications, from geological CO2 sequestration to microfluidics. Due to the interactions between the fluids and the solid walls, fluid invasion undergoes a wetting transition from complete displacement at low displacement rates to leaving a film of the defending fluid on the confining surfaces at high displacement rates. While most real surfaces are rough, fundamental questions remain about the type of fluid–fluid displacement that can emerge in a confined, rough geometry. Here, we study immiscible displacement in a microfluidic device with a precisely controlled structured surface as an analogue for a rough fracture. We analyze the influence of the degree of surface roughness on the wetting transition and the formation of thin films of the defending liquid. We show experimentally, and rationalize theoretically, that roughness affects both the stability and dewetting dynamics of thin films, leading to distinct late-time morphologies of the undisplaced (trapped) fluid. Finally, we discuss the implications of our observations for geologic and technological applications.
DOI: 10.1073/pnas.2303515120
Source: https://www.pnas.org/doi/10.1073/pnas.2303515120