Numerical stability analysis of incompressible boundary layers over ribbed surfaces

Abstract A technology for numerical analysis of the local biglobal stability of laminar incompressible boundary layers over streamwise-ribbed surfaces is proposed. Within its framework, the stability is studied using the locally-parallel approximation and Floquet theory. The work of the proposed technology is demonstrated by the example of a boundary layer over a streamwise-ribbed plate of finite thickness. For the considered values of ribbing parameters, it is shown that the presence of ribbing increases the growth of disturbances compared to a plate without ribbing, thereby promoting the natural laminar–turbulent transition.