Effect of micelle breakage rate on flows of wormlike micellar solutions through pore throats

Abstract

Many practical applications such as enhanced oil recovery or groundwater remediation encounter the flow of viscoelastic wormlike micellar solutions (WLMs) through porous media. A model porous media, consisting of a microchannel with pore throats present in it, is often used to understand the flow dynamics of these complex fluids. This study performs an extensive numerical investigation to understand the complex flow behaviour of these WLMs through such a model porous media based on the two-species Vasquez–Cook–McKinley (VCM) model for micelles. Within the present range of conditions encompassed in this study, we find the existence of an elastic instability once the Weissenberg number exceeds a critical value as it was seen in many prior experimental and numerical studies dealing with polymer solutions. However, for the present case of a WLM solution, we observe that the micelle breakage rate greatly influences these instabilities. In particular, we observe that the intensity of this instability (characterized by the fluctuating flow field) increases with the Weissenberg number up to a critical value of it. Beyond that, it starts to decrease on further increment in the Weissenberg number. This is in contrast to that seen in a polymer solution where the flow field gradually transits to a more chaotic and turbulent-like state (the so-called elastic turbulence state) as the Weissenberg number gradually increases. Furthermore, we notice that the flow dynamics of these WLM solutions strongly depend on the type (symmetric or asymmetric), number, and spacing between two consecutive pore throats. Additionally, an extensive discussion on the pressure drop and relative viscosity is presented in the present study. Although this study is carried out for a model porous system, we hope it will facilitate a better understanding of the flow behaviour of wormlike micellar solutions in an actual porous media. • An elastic instability emerges once the Weissenberg number exceeds a critical value. • As the micelles are become progressively easy to break, the tendency of appearing the elastic instability decreases. • A non-monotonic trend in the flow behaviour is observed as the Weissenberg number gradually increases. • The elastic instability strongly depends on the throat type, number of throats, and the spacing between them.