Fluid-fluid interaction during miscible and immiscible displacement under ultrasonic waves

This paper aims at identifying and analyzing the influence of high-frequency, high-intensity ultrasonic radiation at the interface between immiscible (different types of oils and aqueous solutions) and miscible (different types of oil and solvent) fluids. An extensive set of Hele-Shaw type experiments were performed for several viscosity ratios, and interfacial tension. Fractal analysis techniques were applied to quantify the degree of fingering and branching. This provided a rough assessment of the degree of perturbation generated at the interface when the capillary forces along with the viscous forces are effective. Miscible Hele-Shaw experiments were also presented to isolate the effect of viscous forces. We found that ultrasound acts to stabilize the interfacial front, and that such effect is most pronounced at low viscosity ratios. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007