Simulation of Liquid Flowing over Surfaces with Micro-Structure

The exist shear-free air-water interface at the fluid-solid houndary is one important reason for drag reduction of ultrahydrophobic surface. Rectangular microchannel flows with various periodic micro-structured wall by introducing velocity slip boundary condition at low Reynolds number is investigated through computational fluid dynamics simulations(CFD). The purpose of the current study is to numerically find out the effects of periodic micro-structured wall on the flow resistance in rectangular microchannel with the different spacings between microridges ranging from 15 to 60 μm. The simulative results indicate that pressure drop with different spacing between microridges increases linearly with flow velocity and decreases monotonically with slip velocity; pressure drop reduction also increases with the spacing between microridges at the same condition of slip velocity and flow velocity.