Decomposition of time-resolved tomographic PIV

Abstract : An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry (TR-TOMO PIV) capturing all relevant spatial and temporal scales. The measured three-dimensional flow fields have then been postprocessed by the dynamic mode decomposition (DMD) which identifies coherent structures that contribute significantly to the dynamics of the jet. Where the jet exhibits a primary axisymmetric instability followed by a pairing of the vortex rings, dominant dynamic modes have been extracted together with their amplitude distribution. These modes represent a basis for the low-dimensional description of the dominant flow features.