A double vortex sheet model of the viscous flow near the trailing edge of a lifting aerofoil

Classical definitions of boundary layer mass and momentum flux deficiency thicknesses can lead to gross errors when applied to measurements near a trailing edge where the flow curvature in the free stream is appreciable. This paper presents a double vortex sheet model as a development from the single vortex sheet model of Helmholtz and others. Two bound vortex sheets define a potential function which can describe a flow with the same mass and momentum flux deficiencies as the viscous regions. The bound nature of these sheets allows the modelling of the integral properties of these regions while retaining the advantages of a potential flow. The application to the flow near the trailing edge of a lifting aerofoil is given