Electro-osmosis-driven micro-channel flows: A comparative study of microscopic particle image velocimetry measurements and numerical simulations

This paper presents global and point-wise comparisons of experimental measurements and numerical simulation results of electro-osmotically driven flows in two elementary micro-channel configurations, a straight channel with a groove and a T-junction channel. The microchannels are made by photolithography using poly-dimethylsiloxane (PDMS), a type of silicon product, which is transparent, and electro-osmotically permeable to a variety of liquids. A microscopic particle image velocimetry system has been developed to measure full field velocity distributions by tracking the fluorescence images of 500-nm diameter fluorescene dye particles. The numerical algorithm is based on a spectral element formulation of incompressible Navier-Stokes equations with electro-osmotic forcing. The algorithm utilizes modal expansions in mixed quadrilateral and triangular meshes, enabling complex geometry discretizations with spectral accuracy. Comparisons of experimental and numerical results show good agreements, validating both numerical and experimental methodologies.