Horseshoe vortex

[1][2] A starting vortex is shed as the wing begins to move through the fluid.

The downwash is associated with induced drag and is a component of the system of trailing vortices.

[5] Nevertheless, the simpler horseshoe vortex model used with a reduced effective wingspan but same mid-plane circulation provides an adequate model for the flows induced far from the aircraft.

This effect is amplified by the presence of a low-rise building just upwind.

[8] They can cause scouring of bed materials from both upstream and downstream of the pier.

A horseshoe vortex caused by a (purely theoretical) uniform lift distribution over an aircraft’s wing. The starting vortex is also shown.
Any spanwise change in lift distribution sheds a trailing vortex, according to the lifting-line theory . The starting vortex is also shown.
A realistic lift distribution causes the shedding of a complex vorticity pattern behind the aircraft.