Three-Dimensional Aerofoil (Finite Wing) Theory Describe the vortex representation of aerofoils. On what theoretical and practical observations does it depend? A vortex filament has a strength of 60ms1 and is placed normal to a stream o 40ms velocity. Determine the angular change of local flow direction at a poin 0.8m downstream of the vortex filament if: (i) the vortex filament is infinitely long. (ii) the vortex filament is 1.6m long and the distances form the point to both ends of the vortex filament are equal. (Answers: 16.620, 11.910)