Flow dynamics of wormlike micellar solutions through a model porous media

TL;DR

This study numerically investigates the flow dynamics of wormlike micellar solutions in model porous media, revealing how micelle breakage influences elastic instability and flow behavior at different Weissenberg numbers.

Contribution

It introduces a detailed numerical analysis of WLM flow in porous media using the VCM model, highlighting the effects of micelle breakage on flow instability and turbulence.

Findings

Elastic instability occurs beyond a critical Weissenberg number.

Micelle breakage suppresses flow fluctuations at high Weissenberg numbers.

Flow dynamics depend on pore throat geometry and spacing.

Abstract

The flow of viscoelastic wormlike micellar solutions (WLMs) in porous media is encountered in many practical applications like enhanced oil recovery or groundwater remediation. To understand the flow dynamics of these complex fluids in porous media, a model porous media consisting of a straight microchannel with micropore throats present in it, is very often used. In this study, we perform an extensive numerical investigation to understand the flow dynamics of wormlike micellar solutions based on the two-species Vasquez-Cook-McKinley (VCM) model for micelles through such model porous media. We find the existence of an elastic instability once the Weissenberg number exceeds a critical value; likewise, 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 this elastic instability is greatly influenced by the breakage and reformation mechanisms of the wormlike micelles. In particular, we notice that the intensity of this instability (characterized by the fluctuating flow fields) increases as the Weissenberg number increases; however, beyond a critical value of it, this elastic instability and/or the flow field fluctuation is suppressed because of the breakage of long micelles. This is in contrast to the polymer solutions for which the flow field gradually transits to a more chaotic and turbulent-like state (or the so-called elastic turbulence state) as the Weissenberg number gradually increases. Additionally, we observe that the flow dynamics of these WLM solutions are strongly dependent on the type of micropore throat, the number of pore throats, and the spacing between two consecutive pore throats. An extensive discussion on the pressure drop and apparent viscosity is also presented in the present study.