Effect Of Structural Parameters On The Flow Resistance Of Superhydrophobic Microchannels In Turbulent Regime

In recent years,inspired by hydrophobic property of water strider,fish scales and lotus leaves,reseachers have paid incresinge attention to design and prepare the superhydrophobic surfaces.which have good application prospects in microfluidic devices and antifouling materials.In nature,most of the superhydrophobic surfaces are based on the Cassie model,and the surface rough microstructures is one of the important causes of hydrophobicity.Under the effect of surface tension,when the fluid flows through the superhydrophobic surfaces,gases are trapped in the rough microstructures,and forming a solid-liquid-gas three-phase contact surfaces,to a large extent,the area of the solid liquid direct contact on the superhydrophobic surface is reduced,which reduces the adhesion between the fluid and the superhydrophobic surfaces,resulting in decreasing the viscous resistance.The researches on the flow and resistance characteristics of superhydrophobic surfaces showed that the main structural parameters have significant influence on the flow and resistance characteristics of superhydrophobic,the study on the characteristics of the internal flow in the superhydrophobic microchannels in turbulent regime is not perfect.Therefore,this thesisr has emphatically studied the effect of the main structural parameters on flow and resistance characteristics of superhydrophobic microchannels in turbulent regime.The main contents are as follows:(1)For the resistance and flow characteristics in superhydrophobic microchannels with transverse microstructures,the VOF model and the Realizable k-? turbulence model are employed to simulate three-dimensional constant flow field in the microchannels of the superhydrophobic surfaces with given the boundary conditions of a linear gas-liquid interface and non-slip solid-liquid interface.The flow kinematics characteristics in superhydrophobic microchannels are examined in the turbulent regime,and the effects of the Reynolds number,groove depth,groove width,microchannel width and micro-channel height on the resistance characteristics are analyzed.(2)In order to further investigate the effect of the main structural parameters on the resistance and flow characteristics in superhydrophobic microchannels comprehensively,for the turbulent flow in the superhydrophobic microchannels with longitudinal microstructures,three-dimensional constant numerical simulation is carried out,and the effects of the Reynolds number,free shear area ratios,groove width,microchannel width and microchannel height on the resistance characteristics are discussed;furthermore,the resistance characteristics of superhydrophobic microchannels with longitudinal and transverse microstructures are compared.