Frequency-wavenumber spectral estimation of the wall-pressure field beneath a turbulent boundary layer

The application of two nonlinear data-adaptive techniques to the problem of estimating the frequency-wavenumber spectrum of the pressure field beneath a Turbulent Boundary Layer has been investigated. Although the Maximum Likelihood Method (MLM) exhibits greater bias at wavenumbers below the convective ridge. Monte Carlo simulations demonstrate that its variance at each wavenumber is smaller than that of the Maximum Entropy Method and is, therefore, preferred in cases of limited numbers of sensors and snapshots of data. Subspace extension of the MLM is shown to improve its performance at low wavenumbers.