Multi-Time-Delay LSE-POD Complementary Approach Applied to Wake Flow Behind a Bluff Body

An understanding of the near wake dynamics of a bluff body is desired to better link base drag reduction observed on these bodies with the coherent structures in the wake. This investigation explores different Linear Stochastic Estimation-Proper Orthogonal Decomposition (LSE-POD) methods that can be employed to estimate the dynamics of the energy containing structure. Statistically independent two-dimensional PIV measurements and time-resolved surface pressure measurements are used to determine spatial POD modes and LSE coefficients for estimating the time-varying POD coefficients using measured surface pressures. These results are used with the time-resolved surface pressure measurements to estimate the time-varying POD coefficients that may be used for a low-order, time-resolved reconstruction of the flow field. The multi-time LSE approach formulated in the time domain (multi-time-delay LSE) is found to be successful in capturing the important near wake dynamics.