摘要：In order to clarify the laminar drag reduction and the slip velocity on a hydrophobic surface, the pressure loss of a rectangular duct was measured while applying various types of wall surface qualities to the duct inner wall. Test wall surfaces were classified into three types according to surface characteristics, which were a hydrophobic coating surface, a fine rectangular groove surface, and a fine rectangular groove with a hydrophobic coating. The directions of the fine rectangular groove are parallel, vertical, and random in the flow direction, and the widths are 5 and 10 μm. For fine rectangular grooves with a hydrophobic coating surface, it was clarified that the laminar drag reduction occurred in the Reynolds number range of 150 < Re < 770. The maximum drag reduction ratio is approximately 13% at Re = 649. The Reynolds number range in which the drag reduction occurred increased with decreasing width of the groove, and the direction of the grooves did not affect the drag reduction effect.
