A Simple and Highly Effective Method to Control Interfacial Instability by Leveraging Flow Geometry

Researchers at Princeton University have developed a simple, easily implementable, highly effective, and accurate solution to control fluid interfacial instabilities.  The researchers discovered that the simplest heterogeneity in the flow passage can lead to fundamentally different displacement behaviors. This finding can be leveraged to either inhibit or trigger an instability and, hence, to devise a strategy to manipulate instabilities in fluid-fluid systems. The control setting identified has a wide spectrum of applications ranging from small-scale technologies such as microfluidics to large-scale operations such as enhanced oil recovery.

The displacement of one fluid by another is one of the most common processes involving interfacial instabilities.  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.  In most cases, interfacial instabilities hinder the operation of processes and limit their efficiency.  Moreover, instabilities at the interface of two distinct fluids 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 non-turbulent systems and small-scale devices.  Depending on the application, either a stable or an unstable interface is desirable, thus the ability to control interfacial instabilities is essential in design and technology.