Question

Select the incorrect statement regarding the terminology used in the study of incompressible flow over finite wings.

(a) Induced drag is finite

(b) Circulation is constant

(c) Downwash is absent

(d) Vorticity induces velocity

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This is a very interesting question from The Vortex Filament, the Biot-Savart Law, Helmholtz Theorem topic in division Flow over Airfoils over Finite Wing of Aerodynamics

Answer 1

Right option is (c) Downwash is absent

Explanation: Due to the presence of downwash, lift is no more vertical. The induced drag is caused by the non-vertical component of lift. Circulation is constant, as the Kelvin’s circulation statement states. The vortex filament induces velocity, which depends on the strength of vortex (constant circulation).