Abstract
We studied the mechanism of drag reduction due to textured hydrophobic surfaces in Newtonian laminar flow through a rectangular channel. The test wall surfaces were fabricated with different fine groove patterns and groove area ratios, and were then coated with PTFE to produce hydrophobic surfaces. Drag reduction was estimated by pressure loss measurements in a 12 × 12 mm channel. Visualization of the gas-liquid interface was carried out using a 0.5 × 5 mm microchannel to investigate the mechanism of drag reduction. A series of experiments showed that the gas-liquid contact area ratio and the air layer thickness influence the drag reduction, the maximum drag reduction ratio is 3.7 %.
