Nonlocalized Receptivity to Vortical Free-Stream Disturbances
Perturbation methods are used to analyze the nonlocalized receptivity of a Blasius boundary layer over a wavy surface. At first order two modes are calculated: a steady wall mode resulting from the surface waviness, and an unsteady vortical mode resulting from a free-stream disturbance. These modes interact at second order to produce a forced traveling-wave mode. Receptivity results from an energy transfer between the forced traveling-wave mode and the eigenmode when the forcing is near resonance. Total receptivity amplitudes are an order of magnitude larger than for localized vortical receptivity, but an order of magnitude smaller than for nonlocalized acoustic receptivity.
KeywordsForced Mode Nonlocalized Receptivity Acoustic Receptivity Wall Mode Receptivity Amplitude
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