On the linear stability of swept attachment-line boundary layer flow. Part 2. Non-modal effects and receptivity

Following the study of the spectral properties of linearized swept Hiemenz flow (see Part 1, Obrist & Schmid 2003) we investigate the potential of swept Hiemenz flow to support transiently growing perturbations owing to the non-normal nature of the underlying linear stability operator. Transient amplification of perturbation energy is found for polynomial orders higher than zero, and a catalytic role of the continuous modes in increasing transient growth is demonstrated. The adjoint stability equations are derived and used in a numerical receptivity experiment to illustrate the scattering of vortical free-stream disturbances into the least stable boundary layer mode.