Triboelectric treatment of or addition to a wing tip and an airfoil upper and lower surfaces is selectively done to electrostatically mutually charge the wing tip and the airfoil upper and lower surfaces with the atmospheric air frictionally coming in contact, in order to reduce trailing-edge vorticity and to promote interlayer mixing in the downwash. Electrostatic forces impede air rollup around the wing tip by first pulling the rolling up air from the airfoil lower surface to the wing tip side face, holding, charging and then repelling the rolling up air to the airfoil upper surface. Triboelectric layers with opposite charges, stacked chord-wise or thickness-wise, form flat and rounded wing tips for vorticity and BVI-noise reduction. For similar effects, opposite triboelectric layers, stacked span-wise, form a rounded wing tip. Lining of thick trailing edge of an airfoil is done with a triboelectric beading to reduce trailing-edge vorticity and form drag.