THE EFFECTS OF DISPLACEMENT INDUCED BY THERMAL PERTURBATIONS ON THE STRUCTURE AND STABILITY OF BOUNDARY-LAYER FLOWS

The free-interaction influence of a thermal expansion process in bound ary-layer gas flow is analyzed using the formalism of triple-deck theo ry. The physical model considered is the forced convection of a gas fl owing 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 ther mal perturbation on boundary-layer stability (lower branch) is studied and first-order correction of the lower branch neutral stability curv e for the boundary-layer flow has been obtained. The shift of neutral stability is then computed for different values of the thermal perturb ation wave number, making unstable some otherwise stable modes.