Microscopic Textured Surfaces for Micro-Fluidic Applications

Many attempts have been made to fabricate textured surfaces that imitate the configurations of naturally occurring surfaces, the most common being the hierarchical microstructure on a lotus leaf. In addition, numerical simulations have also been performed to evaluate limited variations in the configurations of the textured surfaces. However, in reality, the surfaces occurring in nature have numerous variations. In this work, an attempt is made to consider a few of these variations on a surface bearing micro-pillars used in a micro-channel. The variations in the surface texture geometry include a change in the orientation, height, and corner radius of micro-pillars. Numerical simulations are performed using CFD-based methods to evaluate the pressure drop across the micro-channels bearing the textured surfaces on their bottom face. It is observed that the surfaces bearing uniform, upright pillars offer the least resistance to fluid flow while flat surfaces offer the highest resistance. While the orientation of the pillars with respect to flow direction does not change the pressure drop significantly, the pillars with rounded edges and the pillars with larger standard deviations in their heights offer considerably more resistance to the flow of fluid than the uniformly upright pillars. This study will help designers to incorporate these variations in their surface design to obtain the desired results.