Chapter 14. Process Flow of Wormlike Micelle Solutions in Simple and Complex Geometries

Abstract

This chapter summarizes recent efforts to evaluate and enhance the predictability of process flows involving wormlike micelle (WLM) solutions. We focus on two extremes of laminar flows. First we explore the predictability of pressure drop in laminar pipe flow, arguably the simplest process flow. Second, we explore the laminar flow in static mixers, which are a complex geometry analogous to porous media. We utilize a model WLM system that is a mixture of commercially relevant surfactants. Rheological properties of this model system are measured as a function of salt content, or at various compositions along the salt curve. We conduct this exploration using NMR-velocimetry for laminar pipe flow and investigate the applicability of static mixer flow models. Our first conclusion is that models using apparent wall slip enable pragmatic modelling and analysis of laminar pipe flow. Our second conclusion is that the linear viscoelastic complex viscosity is the appropriate effective viscosity for modelling static mixer flows, where shear banding is unlikely to occur.