Spatiotemporal analysis of fluctuating base pressure and velocity in a blunt trailing edge wake

Three-dimensional instabilities in the wake of a blunt trailing edge profiled body are examined through experimental measurements of velocity and the spanwise distribution of fluctuating surface pressure on the model rear face near separation. Spatial and temporal variability of the vortex shedding behaviour result in low-frequency modulation of the pressure signals. The time-dependent amplitude is characterized using the wavelet transform, while subsequent correlation analysis and reduced-order modelling provide quantitative evidence of the dominant influence of large-scale instabilities. The cross-correlation of the wake velocity and the surface pressure are examined in the framework of the Extended Proper Orthogonal Decomposition, through which reduced-order models of the measured variables are related to construct an empirical estimator of velocity. Implications of the observed modal correlations and the statistical signature of large-scale spatial variations are discussed in relation to the estimation of multi-scale wake phenomena.