Determining the Spectral Signature of Spatial Coherent Structures
  We applied to an open flow a proper orthogonal decomposition (pod) technique, on 2D snapshots of the instantaneous velocity field, to reveal the spatial coherent structures responsible of the self-sustained oscillations observed in the spectral distribution of time series. We applied the technique to 2D planes out of 3D direct numerical simulations on an open cavity flow. The process can easily be implemented on usual personal computers, and might bring deep insights on the relation between spatial events and temporal signature in (both numerical or experimental) open flows. 
L.R. Pastur (LIMSI), F. Lusseyran (LIMSI), Y. Fraigneau (LIMSI), B.   Podvin (LIMSI)