Goldstein and Hultgren(1989) and Kerschen (1990). A detailed review of some experiments on receptivity are presented in Nishioka and Morkovin (1986).In the prediction of boundary-layer receptivity to freestream long-wavelength disturbances, theoretical investigations based on high-Reynolds-number asymptotic methods have identified that the conversion of freestream disturbances to "IS instability waves takes place in the boundary layer where the mean flow exhibits rapid local variations in the streamwise direction [Kerschen (1990,1991), Goldstein (1983,1985]. The discussions here concentrate on receptivity to sound in the leading-edge region. A few experiments, using fiat plates with elliptic leading edges, have been done on boundary-layer receptivity to freestream sound. In Leehey and Shapiro (1980)

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Here we discuss the computational modeling of the receptivity of the laminar boundary layer on a semi-infinite flat plate with an elliptic leading edge. The incompressible flow is computed in a spatial simulation using the full Navier-Stokes equations in general curvilinear coordinates. Finite differences are used in both space directions and in time. First, the steady basic state is obtained in a transient approach using spatially varying time steps. Then, small-amplitude acoustic disturbances of the freestream velocity are applied as unsteady boundary conditions, and the governing equations are solved time-accurately to evaluate the spatial and temporal developments of instability waves (Tollmien-Schlichting waves) in the boundary layer. A sharper leading edge is found to be less receptive to freestream disturbances.

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