The strong vortex produced by the wingtip spillage is called Vortex Sheet. The Bound Vortex describes actually the airflow as it follows the airfoil boundary. A Starting Vortex is a product of circulation around an airfoil. A combination of these vortices generates an area of Downwash Field which is trailing behind the wing. The illustration to the right demonstrates how the downwash changes in the airflow and contributes to drag.
Vector represents the vertical flow caused by the downwash.
The vector D shows an additional drag force that would not otherwise present. This additional drag is called induced drag. The new angle of attack is greater than angle of the original angle of attack thus increasing both lift and drag at the wingtips area. This additional drag occurs without an apparent change of the angle of attack but by an induced change. This drag is affecting a limited portion of the wing.