Direct Numerical Simulation of Turbulence Onset in Supersonic Boundary Layer Over a Parabolic Profile

Laminar–turbulent transition in the boundary layer over a parabolic profile of a straight wing with a relative thickness of 10% is investigated. Freestream conditions correspond to the standard atmosphere at an altitude of 20 km and a Mach number of 3. Disturbances are introduced by a continuously operating blowing–suction actuator, which generates a relatively narrow initial frequency–wavenumber spectrum of perturbations. Direct numerical simulation is performed by solving the full unsteady compressible Navier–Stokes equations for a perfect gas. An analysis of mass-flux perturbations and their frequency–wavenumber spectra is carried out at various streamwise distances from the disturbance generator. The spatial distribution of the coherence function is presented.