Experimental Investigation of Plug Flow Hydrodynamics in a T-Junction Rectangular Microchannel

Abstract

This study experimentally investigates the hydrodynamics of plug flow in a rectangular T-junction microchannel using various fluid systems with different viscosity ratios. Three key parameters, plug length, plug velocity, and plug shape, were systematically analysed as functions of the flow rate ratio, capillary number, and viscosity ratio. The results show that the interplay between viscous forces, inertial forces, and interfacial tension at the junction strongly governs droplet/plug formation and length. Comparisons with existing correlations in the literature show excellent agreement with the experimental data. A power-law model was found to be a better predictor of plug velocity than a linear model. The viscosity ratio was found to affect plug velocity significantly. Furthermore, the study shows that the final plug shape is determined by both system design and fluid properties. Channel geometry, and junction configuration were found to influence plug morphology, particularly curvature radii of the front and rear. These findings provide valuable insights for optimising the design and performance of microchannel-based heat sink systems.