Abstract
The instability of the boundary layer on two-dimensional (2-D) surface corrugation was examined experimentally. The corrugation amplitude Aw was one order of magnitude smaller than the displacement thickness of the boundary layer. Sinusoidal-geometry corrugations with various wavelengths were considered to see how the growth of Tollmien-Schlichting (T-S) waves was affected by the scale of corrugation. The corrugation wavelength λw ranged from about one-tenth to the same order as the T-S wavelength. The destabilizing effect of the 2-D corrugation was observed for a wide range of corrugation wavelengths and was not strongly dependent on the wavelength. Even when a separation bubble was formed in each furrow for the smallest wavelength, the amplification of T-S waves was almost the same as in the case of longer wavelengths.
