Optical Measurements in the Wake of a Circular Cylinder of Finite Length at a High Reynoldsnumber

The flow around a cylinder of finite length with one end bound on a large end plate defines a challenging problem for both, the numerical simulation and the experiment. In the following article, some of the results are described which were obtained experimentally on this “Leitexperiment” during the DFG research priority program 1147. The emphasis is placed on the observation of the highly unsteady wake using time resolved particle image velocimetry. Here a large amount of data was inferred, resolving both, the spatial domain on a volume of 2D planes as well as the temporal domain by measuring fields of the 3D velocity vector at a rate of 1000 Hz. After a short introduction into the features of the time average flow field, a new approach is taken, using the POD as an instrument to reconstruct the unsteady 3D flow field from ensembles of instantaneous 2D TR-PIV fields containing the complete velocity vector. The POD modes from this were compared successfully with the results of the numerical simulation, performed simultaneously in the same research priority program [2].