A microchannel flow with presence of micro-post arrays on channel top wall

Abstract

A microchannel flow is considered and the influence of the micro-post arrays and air trapped on velocity and temperature increase of the working fluid is examined experimentally and numerically incorporating 3-D simulations. The channel bottom plate is considered to be smooth and hydrophilic, which moves with a constant velocity, while channel top wall is stationary and it has staggered arrangement of micro-post arrays with hydrophobic wetting state. An experiment is carried out to validate velocity and temperature predictions while setting simulation conditions in line with the experiments. It is found that the flow field in top channel wall vicinity is influenced by the micro-post arrays; hence, wavy flow field is generated in this region. Flow circulation in the trapped air in between the micro-post arrays influences the heat transfer rates. The Nusselt number reduces slightly with increasing pitch size of the micro-post arrays. In addition, increasing the microchannel height lowers the Nusselt number. The pressure drop between the channel inlet and exit is influenced significantly by the micro-post arrays. Increasing pitch size of the micro-post arrays reduces the pressure drop; however, further increase of the pitch size beyond 12 μm does not alter the pressure drop across the microchannel.