Flow of Power-Law Liquids in a Hele-Shaw Cell Driven by Non-Uniform Electroosmotic Slip in the Case of Strong Depletion

TL;DR

This paper investigates the flow of power-law non-Newtonian fluids with wall depletion in a Hele-Shaw cell driven by non-uniform electroosmotic slip, deriving equations and analyzing solutions for microfluidic applications.

Contribution

It derives a p-Poisson equation for pressure and provides asymptotic approximations for non-Newtonian electroosmotic flow, aiding microfluidic system design.

Findings

Asymptotic approximation agrees well with exact solutions.

Non-Newtonian properties significantly influence pressure and velocity fields.

Analysis applicable to microfluidic electro-kinetic transport systems.

Abstract

We analyze flow of non-Newtonian fluids in a Hele-Shaw cell, subjected to spatially non-uniform electroosmotic slip. Motivated by their potential use for increasing the characteristic pressure fields, we specifically focus on power-law fluids with wall depletion properties. We derive a p-Poisson equation governing the pressure field, as well as a set of linearized equations representing its asymptotic approximation for weakly non-Newtonian behavior. To investigate the effect of non-Newtonian properties on the resulting fluidic pressure and velocity, we consider several configurations in one- and two-dimensions, and calculate both exact and approximate solutions. We show that the asymptotic approximation is in good agreement with exact solutions even for fluids with significant non-Newtonian behavior, allowing its use in the analysis and design of microfluidic systems involving electro-kinetic transport of such fluids.