LINEAR-STABILITY OF DIFFERENTIALLY HEATED SPATIALLY DEVELOPING LAYERS

Heterogeneous shear layers, characterized by the presence of a wake de ficit and a Gaussian temperature profile, me considered. Unstable mode characteristics are interpreted in terms of a Eve-parameter set which describes the velocity ratio and the thicknesses and strengths of the wake component and temperature spike. In the absence of a wake defici t, the Kelvin-Helmholtz mode is inhibited as density gradients increas e. Stabilization of this mode is weak (strong) when the density profil e thickness is larger (smaller) than that of the shear layer When a wa ke component is present, stabilization of the Kelvin-Helmholtz instabi lity is no longer observed, In this case, the growth rate of unstable Kelvin-Helmholtz waves is found to be weakly sensitive to the presence of a heated region and to the details of the wake deficit.