downwash

thumb|upright=1.14|The effect of downwash from a hovering Sikorsky Seahawk is clearly visible on the surface of water below.

In aeronautics, downwash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift. In helicopter aerodynamics discussions, it may be referred to as induced flow.