RECEPTIVITY OF AXISYMMETRICAL BOUNDARY-LAYERS DUE TO EXCITATION BY A DIRAC POINT-SOURCE AT THE WALL

The receptivity of an axisymmetric boundary layer excited by a Dirac point source at the wall of a cylindrical body has been investigated on the basis of a parallel-flow approximation. The unstable part of the disturbed flow field has been extracted and discussed. As a measure of the receptivity, the production integral and its axial derivative immediately downstream of the source position is used. For two different mean velocity profiles with inflexion points these quantities have been calculated. Furthermore, the axial variation of the production integral is presented for two different sets of flow parameter values and the development of the RMS-values for the unstable axial velocity fluctuation is shown.