Low Wavenumber Models for Turbulent Boundary Layer Excitation of Structures

When the spatial correlation length of the turbulent boundary layer (TBL) pressure fluctuations is small compared to the structural wavelengths, the vibration response can be determined by forming an equivalent point drive from the effective correlation area. This approach is equivalent to using the zero wavenumber component of the TBL pressure spectrum, so it only works for TBL models that are wavenumber white at low wavenumbers. In this work, a similar simplification is developed for TBL models with a wavenumber-squared dependence, that works for structural modes with a low-pass cutoff wavenumber. This introduces a boundary layer thickness dependence that results in significantly different predictions for structures excited by a developing boundary layer. Based on the analysis, an experimental setup is proposed that may help resolve some of the controversy surrounding the low wavenumber TBL spectrum.