Frictional drag reduction in microchannel using slip on convex air bubbles naturally formed in a specifed a cavity

This paper presents the reduction of frictional drag by using the slip on the interface of convex air bubble. The visualization shows that the convex bubbles formed naturally in the hydrophobic cavity array positioned along a microchannel with time. The size of the bubbles depended on the size of the cavity size. The velocity distribution was also displayed by using a micro-PIV measurement. Then, the volume flow rate and the momentum were examined by increasing inlet flow rate for the different sizes of microbubble. The maximum reduction of frictional drag of 52 % was obtained.