Drag reduction effect of ultraviolet laser-fabricated superhydrophobic surface

Superhydrophobic (SH) surface has been found effective for drag reduction in wall-bounded turbulence for decades, especially the metallic durable SH surfaces are believed very promising for improving the velocity and voyage of marine vehicles. We present stainless steel SH surfaces with U-groove patterns that fabricated by ultraviolet laser texturing and coating modifier treatment. The drag-reducing effects of the SH surfaces are tested by a self-built gravity sliding speed improving evaluation device. The results show that the different drag-reduction performance of the SH surfaces can be achieved by adjusting the line spacing of the crossing U-groove patterns. With the line spacing equalling to 80 mu m, the ultraviolet laser textured stainless steel SH surface acquires the static contact angle of 161.5 degrees and the dynamic sliding angle of only 2 degrees, which leads to the maximum speed improving rate of 29.7%.