Confluence of Wall Shear Stress and its Relation to Vorticity Surface Flux

Abstract

Methods stemming from Vortex Dynamics have the potential to support the aircraft design and optimization process. In particular, the analytical description of wall bounded vorticity flux allows to identify promising quantities which could be manipulated in order to reduce overall drag and increase lift. It also reveals the connection between surface forces acting on an aircraft and its geometrical shape contour, but also the pressure and viscous flow related fluxes. By investigating the sources of wall-shear stress and using elements of the boundary vorticity flux relations an analytical extension could be derived allowing to identify the flow physical relations to wall-shear flow pattern, expressed by the quantity confluence, and to flow separation criteria. These derived quantities are visualized on the surface of a DLR wide body aircraft configuration.