Drag characteristics of a turbulent boundary layer over a flat plate with transverse square grooves

Abstract The effect of transverse square grooves on the drag characteristics of a flat plate has been investigated using direct drag measurements in a tow tank. Two flat plates with 2.5 and 5 mm transverse square grooves, with groove spacing (s) to groove width (w) ratio, s/w=10, 20 and 40, were tested at plate length Reynolds numbers in the range 2–10×106. There is an increase in drag over the “smooth” plate for all s/w configurations.