LOCALIZED RECEPTIVITY OF THE BOUNDARY-LAY ER

An investigation of the generation of Tollmien-Schlichting waves has b een carried out with the direct numerical simulation PEGASE code devel oped at ONERA. The latter was allowed to visualise these waves in a tw o-dimensional incompressible pow around a roughness element placed on a pat plate, the incoming flow having the form: U-infinity = U-0(1 + e psilon cos omega t). Quantitative results on the influence of epsilon, and of the dimensions h and I of the rectangular hump on these waves are obtained from a parametric study. These results show good agreemen t with previous experimental and theoretical studies.