POD eduction of coherent structure

The figures below show the eduction of the large scale structure by the POD. The first figure, (a), shows the velocity directly out of the hot-wire anemometer probes and the following figures show how the first radial POD mode and various combinations of azimuthal Fourier modes, m, are able to filter the small scale structure out and leave only the coherent structure. Note the local mean is subtracted off at each measurement point.

(a) Original Velocity (b) First radial POD mode,
All azimuthal modes,m

(c) First radial POD mode,
(d) First radial POD mode,

(e) First radial POD mode,