Incompressible turbulent flow at the leading edge of swept wings

Due to a singularity in the governing three-dimensional turbulent momentum integral equations at the attachment line, low order infinite-swept and swept-tapered CFD methods employing the viscous-coupling technique have been unable to model attachment line transition or contamination without approximating the development of the boundary layer immediately downstream of a turbulent attachment line. An experimental study was therefore conducted to explore the flow near a turbulent attachment line, which showed considerable differences to the numerical approximation. On the basis of the experimental data; a modification to the governing equations in the attachment line region has been proposed and tested. Comparisons with experimental measurements show that the proposed numerical model is not only able to predict the flow to within ±5%, but it also captures the non-monotonic behaviour of the momentum thickness, in the vicinity of the attachment line, which has not been reported previously.