Edery Yaniv, Berg Steffen, Weitz David
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Shell Global Solutions International B.V., Kesslerpark 1, 2288 GS Rijswijk, Netherlands.
Phys Rev Lett. 2018 Jan 12;120(2):028005. doi: 10.1103/PhysRevLett.120.028005.
We use confocal microscopy to measure velocity and interfacial tension between a trapped wetting phase with a surfactant and a flowing, invading nonwetting phase in a porous medium. We relate interfacial tension variations at the fluid-fluid interface to surfactant concentration and show that these variations localize the destabilization of capillary forces and lead to rapid local invasion of the nonwetting fluid, resulting in a Haines jump. These spatial variations in surfactant concentration are caused by velocity variations at the fluid-fluid interfaces and lead to localization of the Haines jumps even in otherwise very uniform pore structure and pressure conditions. Our results provide new insight into the nature of Haines jumps, one of the most ubiquitous and important instabilities in flow in porous media.
我们使用共聚焦显微镜来测量在多孔介质中，含有表面活性剂的被捕获的润湿相和流动的侵入性非润湿相之间的速度和界面张力。我们将流体 - 流体界面处的界面张力变化与表面活性剂浓度联系起来，并表明这些变化使毛细作用力的失稳局部化，导致非润湿流体的快速局部侵入，从而产生海恩斯跃变。表面活性剂浓度的这些空间变化是由流体 - 流体界面处的速度变化引起的，并且即使在其他方面孔隙结构和压力条件非常均匀的情况下，也会导致海恩斯跃变的局部化。我们的结果为海恩斯跃变的本质提供了新的见解，海恩斯跃变是多孔介质流动中最普遍且重要的不稳定性之一。
