Application of POD Techniques to the Far Jet

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PROJECT SUMMARY The dynamics of the fully-developed axisymmetric far jet using Proper Orthogonal Decomposition (POD) techniques will be investigated experimentally. The overall goal is to obtain a better understanding of the structure of the far jet, and the degree to which its evolution is foreshadowed by the near jet. The experiment has two specific objective: * First, POD techniques will be applied to extensive measurements of the velocity cross-spectra in order to determine the eigenfunctions describing the far jet. * Second, the eigenfunctions determined will be used to reconstruct the instantaneous flow, both spatially and temporally, in whole or in part. The investigation will use two unique experimental apparatus: one a 138 hot-wire probe developed earlier to study the jet mixing layer; the other a flying array of 15 hot-wire, the spacing of which changes with downstream distance from the jet exit. These techniques will be used in conjunction the known one- and two-point similarity properties of the far jet to determine the spatial and temporal evolution of the POD eigenfunction which comprise the flow (including their streamwise dependence)