The effects of displacement induced by thermal perturbations on the structure and stability of boundary-layer flows

Abstract

The free-interaction influence of a thermal expansion process in boundary-layer gas flow is analyzed using the formalism of triple-deck theory. The physical model considered is the forced convection of a gas flowing over a flat plate subject to a heated slab. Both linearized and full nonlinear solutions are obtained using Fourier transform methods and spectral numerical techniques. The influence of monochromatic thermal perturbation on boundary-layer stability (lower branch) is studied and first-order correction of the lower branch neutral stability curve for the boundary-layer flow has been obtained. The shift of neutral stability is then computed for different values of the thermal perturbation wave number, making unstable some otherwise stable modes.