Scaling of turbulent wall pressure fluctuations downstream of a rearward facing step

The turbulent boundary layer that forms downstream of a surface discontinuity is locally inhomogeneous. Here, we consider the boundary layer that occurs downstream of a rearward facing step discontinuity on a flat plate that is exposed to a zero incidence, uniform subsonic flow. The wall pressure "point" spectra are measured by small, flush-mounted pressure transducers located at various locations downstream of the step. A new form of the non dimensional point wall pressure auto-frequency spectrum is proposed that includes the statistical variations of the reattachment location. This form is shown to collapse quite well all of the spectra measured slightly upstream, within, and downstream of the flow reattachment location. (C) 1999 Acoustical Society of America.