An Extended View of the Inner-outer Interaction Model for Wall-bounded Turbulence Using Spectral Linear Stochastic Estimation

Streamwise velocity fluctuations in the inner-region of wall-bounded turbulent flows can be predicted by the model of Marusic, Mathis & Hutchins (2010). Only a single large-scale velocity signal from an outer position in the logarithmic region is needed for the model, and all other parameters are determined from a once-off calibration experiment. Here we elucidate part of the model by investigating the scale-dependent coherence magnitude and phase throughout the boundary layer. The collection of coherent scales exhibits a shift with respect to the reference position that is shown to be independent of scale; thus the large-scales are non-dispersive. Because these scales comprise a strong coherence, their signature in the inner-region is predicted from an input signal acquired at the geometric center of the log-region. Previously this was achieved via single-time stochastic estimation. Here we leverage the inherent advantages of spectral linear stochastic estimation for the prediction of these large-scales.