Receptivity of Hypersonic Boundary Layers to Kinetic Fluctuations

Abstract

The receptivity of high-speed compressible boundary layers to kinetic fluctuations (KF) is considered within the framework of fluctuating hydrodynamics. The formulation is based on the idea that KF-induced dissipative fluxes can lead to the generation of unstable modes in the boundary layer. Using linear stability theory (LST) and a variety of asymptotic methods, the KF-receptivity problem is solved for a range of high-speed flat plate boundary layer configurations. Approaches for solving the KF-receptivity problem in cases where the dominant modes exhibit long scale near-neutral behavior or when two modes of the discrete spectrum coalesce are developed and explored in detail.