Surface pressure fluctuation measurements were made in two-dimensional turb
ulent boundary layers at two Reynolds numbers (Re-theta = 7.3 X 10(3) and 2
.34 X 10(4)) and pressure-driven three-dimensional turbulent boundary layer
s at two Reynolds numbers (approach Re-theta = 5.94 X 10(3) and 2.32 X 10(4
)). The collapse of spectral levels at middle and high frequencies and the
effects of inner and outer boundary-layer scaling variables are shown for a
wide range of Reynolds numbers (1.4 X 10(3) < 2.34 X 10(4)) for the two-di
mensional flows. Such scaling parameters do not collapse the pressure spect
ra beneath three-dimensional hows, which have a nearly constant, or flat, m
idfrequency range, and at some measurement stations and spectral levels wit
hin the flat- and high-frequency spectral ranges that significantly raise p
'. Additionally, dimensional spectral levels within the Bat-frequency range
are independent of Reynolds number. Analysis based on the Poisson equation
shows that the variation of the high-frequency spectral levels is related
to the variation in near-wall mean velocity gradients and nu(2) structure d
ue to the spanwise pressure gradient.