Efficient electrokinetic non-Newtonian flow mixing in a patterned micro-tube.

This article presents a numerical study of electroosmotic mixing of non-Newtonian power-law fluids in an axisymmetric micro-tube featuring sinusoidal wall roughness and periodic zeta potential. Using a finite volume method to solve coupled Poisson-Nernst-Planck and Cauchy momentum equations, the research investigates how wave amplitude (δ), Debye-Hückel parameter (κa), and flow behavior index (n) affect mixing efficiency, pressure drop, and overall mixing performance. Results indicate that increasing δ and n (shear-thickening behavior) enhances vortex formation and mixing efficiency—reaching up to 95%—while higher κa (thinner electric double layer) reduces mixing due to decreased residence time. The study also introduces a mixing performance factor, balancing mixing efficiency against pressure drop, and finds optimal performance near n = 1.35, providing insights for designing efficient passive electrokinetic micromixers for biofluid and polymer transport in microfluidic devices.