DNS of Laminar Turbulent Transition in a D Aerodynamics Boundary Layer Flow

Controlled laminar turbulent transition of a D boundary layer ow caused by localized surface nonuniformities is investigated by means of spatial direct numerical simulations DNS based on the complete incompressible D Navier Stokes equations and a combined th order compact Finite Di erence spanwise Fourier spectral scheme The considered laminar spanwise invariant at plate base ow is a model of the boundary layer ow in the front region of a swept wing with favorable and ensuing adverse chordwise pressure gradient The primary down stream growth and nonlinear interaction of vortex packet modes as well as the appearance of a secondary instability mechanism leading to turbulence is investi gated in detail The e ectiveness of a steady nonlinear upstream ow deformation of the base ow with respect to signi cant transition delay is shown