Theoretical Analysis of Primary Instabilities in Three Dimensional Boundary Layer Flows

摘要

The cross flow instability in negative pressure gradient regions of three-dimensional boundary layers was analyzed using local, linear stability theory. The stability eigenvalue problem was solved, applying a spectral method (Chebyshev collocation). Almost perpendicular to the potential flow direction, propagation low frequency and stationary disturbances are already amplified at low Reynolds numbers, and therefore accentuated with respect to the others. The frequency of the most amplified traveling mode, and the wavelength of the stationary disturbance pattern are in satisfactory agreement with measurements on a swept plate with a pressure-inducing displacement body.