Low energy consumption achieved through hydrodynamic mixing of shear-thinning fluids in compact passive micromixers

Abstract

This study investigates the mixing performance of compact chaotic microdevices for Newtonian and non-Newtonian Shear-Thinning fluids in microfluidic applications. Building upon the notable mixing characteristics of the Two-Layer Crossing Channels Micromixer (TLCCM-X) with Newtonian fluids, we developed modified designs (TLCCM-KX and TLCCM-O) to enhance mixing efficiency. Numerical simulations were conducted using CFD code to solve Navier-Stokes, mass conservation, and species transport equations. The species transport model was implemented to analyze the mixing process of pseudoplastic carboxymethyl cellulose (CMC) solutions, characterized by the power-law model with flow behavior indices ranging from 0.49 to 1 and generalized Reynolds numbers from 0.2 to 70. Mixing effectiveness was evaluated through hydrodynamic mixing degree calculated across various cross-sectional areas, where a value of 1 represents perfect mixing. Our comprehensive analysis included mass fraction contours, streamlines, shear rate curves, pressure drops, Poiseuille number to the hydrodynamic mixing degree (Po/HMD) ratios, and mixing energy costs. Results demonstrate that the TLCCM-O micromixer exhibits the most energy-efficient device among those studied, requiring significantly lower mixing energy costs. This makes the TLCCM-O particularly promising for applications where energy efficiency is critical considerations, representing advancement in micromixer technology for both Newtonian and non-Newtonian fluid applications.