Engineered surface textures can manipulate boundary layers affecting fluid drag. We study periodic, infinitely long spanwise grooves on a laminar boundary layer over a plate for 1000 < R e L < 25000. Below a certain width-to-depth aspect ratio (AR), a primary vortex inside each groove causes the freestream to “slip over”, reducing skin friction. Increasing AR poses a tradeoff in drag reduction due to pressure drag from groove vertical walls. Overall, transverse grooves for laminar flow can reduce total drag up to 10% compared to a flat plate, despite increasing the wetted surface area.
Fluids, Mechanical engineering journal, Fluid mechanics journal
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