Stability of boundary layers over permeable surfaces

The stability of a two-dimensional, incompressible boundary layer over a perforated surface is examined. The spacing of the perforations is assumed to be small compared to the wavelength of the disturbances. If, under the perforations, there exists a chamber that permits traveling waves to exist, it can, under certain conditions, stabilize the flow. If instead there exist small chambers that sustain compressible waves created by the disturbance in the boundary layer, their effect on the stability of the flow is negligible, for the range of frequencies of interest.