Hydrodynamic Characteristics of Textured Microchannel Flow

Microchannel flow is of great interest across many disciplines and applications, from biochemical diagnostics to thermal management systems. Nonetheless, such flow requires large pumping power due to its small cross-sectional length scale. Textured surfaces have shown encouraging results in terms of drag reduction in external flows and at larger scales (turbulent regime). However, there have been some discrepancies in the literature regarding the possibility of drag/friction reduction in microscale internal flows (laminar regime), which is believed to be due to the absence of a proper definition for the reference baseline. The main goal of this paper is to determine whether the (rectangular) textures lead to drag/friction reduction while comparing their results with the correct reference. The rectangular trenches have been introduced on the side walls of the microchannels/microgaps to understand the underlying frictional physics by conducting numerical simulations and experiments. The effect of geometrical parameters of the rectangular trenches as well as the Reynolds number has been investigated on characteristics of the flow. A thorough analysis has been performed using a neural network (NN) to evaluate the potential drag reduction in textured microchannels. The results showed that using the correct reference baseline, no drag reduction was observed in textured microchannels with rectangular trenches. Moreover, the width-to-depth aspect ratio of the trenches and roughness (texture size to mean microchannel dimension) are introduced to be critical parameters in the flow behavior inside textured microchannels.