(499f) Leveraging Flow Geometry to Control Interfacial Instabilities

In most cases, interfacial instabilities hinder the operation of industrial processes. For instance, fluid-fluid instabilities remain a major challenge for enhanced oil recovery processes such as water flooding. On the other hand, these instabilities can be beneficial to chromatographic separation and can improve mixing in small-scale devices. The fact that, depending on the application, either a stable or an unstable interface is desirable makes the ability to control interfacial instabilities essential in design and technology.

It is universally accepted that, in a uniform medium, flow displacement is unstable when a low viscosity fluid invades a fluid of higher viscosity: the classical viscous fingering instability. Consequently, once fluid properties are specified, opportunities for system control become very limited. However, real systems where displacement instabilities occur, such as porous structures, lung airways and printing devices, are rarely uniform. We find that the simplest heterogeneity can lead to fundamentally different interfacial behaviors. We leverage our findings to devise a strategy to manipulate instabilities in fluid-fluid systems.