Official websites use. Share sensitive information only on official, secure websites. To whom correspondence should be addressed. Email: nima. Edited by Tom C. Author contributions: H. Viscous fingering commonly takes place during injection of one fluid that displaces a resident fluid in a porous medium. Fingering normally is promoted where the injected fluid is less viscous than the resident fluid being displaced.
We propose a design of a porous medium in the form of an ordered structure to suppress or trigger depending on the application viscous fingering in porous media without modifying fluid properties or wettability. We utilize pore-scale direct numerical simulations, state-of-art experiments and analysis to derive predictive tools to evaluate effects of various parameters on controlling viscous fingering in porous media.
Moreover, we propose generalized analytical solutions and a phase diagram for the parameter space affecting viscous fingering patterns. Keywords: suppressed viscous fingering, structured porous media, microfluidics, direct numerical simulation, analytical model. Such interfacial instabilities are undesirable in many natural and engineered displacement processes. We report a phenomenon whereby gradual and monotonic variation of pore sizes along the front path suppresses viscous fingering during immiscible displacement, that seemingly contradicts conventional expectation of enhanced instability with pore size variability.
Experiments and pore-scale numerical simulations were combined with an analytical model for the characteristics of displacement front morphology as a function of the pore size gradient. Our results suggest that the gradual reduction of pore sizes act to restrain viscous fingering for a predictable range of flow conditions as anticipated by gradient percolation theory. The study provides insights into ways for suppressing unwanted interfacial instabilities in porous media, and provides design principles for new engineered porous media such as exchange columns, fabric, paper, and membranes with respect to their desired immiscible displacement behavior.
For viscously dominated flows, Hill 9 and Saffman and Taylor 10 were the first to quantify the highly ramified morphology of an interface resulting from displacement of a viscous fluid by a fluid of lower viscosity and so document the emergence of finger-like invasion patterns [viscous fingering VF ]; Hill 9 investigated the process using a packed bed, while Saffman and Taylor 10 employed fluid-filled Hele-Shaw cells to study VF.
