Laminar Instability of Parallel and Nonparallel Flows of Adiabatic Flat Plate

In the present paper, spatial linear stability of adiabatic laminar flat plate boundary layer is computed numerically. This work is interested on the non-parallel compressible flow for a two-dimensional (۲D) and three-dimensional (۳D) disturbances. Stability diagrams, in the form of curves of constant spatial amplification rates are presented and constitute the original contribution of this paper. However, to assess the validity of the present computations, some important results of parallel flow stability are presented in the convenient and familiar form of contours of constant spatial amplification rates for both ۲D and ۳D waves in the Mach number range Me= ۰.۹ to ۲.۲. Comparisons results for the parallel flow agree with those obtained by Mack and Wazzan, Taghavi and Keltner, but differ from the nonparallel flow giving some important spatial stability results and showing the importance of the wave angle ψ and the Mach number, even the stability diagrams presented in this paper concerned the Reynolds number gives different results for the parallel and nonparallel flows.

Keywords:

Laminar instability , Compressible boundary layer , Transonic flow , Stability diagrams , Supersonic flow