Discussion
Despite the availability of a large quantity of literature on viscous
fingering (immiscible and miscible), few have addressed the viscous
finger types that involve chemical interaction. And emulsion
flow—especially that of heavy oil has been mostly neglected. In this
paper, we attempt to address this missing gap by approaching emulsion
flow through fractal analysis and quantification analysis using various
dimensionless numbers. Based on this analysis,
we have provided the phase map to
describe the overall relationship with hydrodynamic stability, surface
tension, and viscosity using the original experimental images. The
fractal dimension (DB) corresponding to each
image has also been provided (Figure 18 ). It can be inferred
that tip-splitting like behavior is associated with miscibility at low
viscosity conditions (and higher fractal dimensions). In this emulsion
flow study, with the hydrodynamic stability loss, droplet formation
begins until it eventually reaches the steady-state of energy and
droplets maintain their shape. The mechanism for the temporary or
permanent halt in the coarsening process in the case of
surfactant-induced fingering requires further investigation—-although
CMC may be suspected to be the cause. In the case of fingering induced
by surfactant and polymer, viscosity plays a significant role in
maintaining the hydrodynamic stability, and surfactant-induced fingers
develop before the development of the polymer-induced fingers (which
also have higher hydrodynamic stability)— which eventually results in
the consumption of surfactant-induced fingers by polymer-induced fingers
via Ostwald ripening. Polymer-induced fingers are characterized by a
smooth frontal mobility line along with a high level of hydrodynamic
stability subsequently rendering droplet generation non-existent.