Abstract: The flow around two bluff bodies in tandem is an interesting
phenomenon whose nature strongly depends on the distance between the bodies. In
this work oil smoke visualizations of the flow around two normal flat plates in
tandem configuration are compared with phase averaged Laser Doppler Anemometry
measurements of the flow field for a full period. Phase averaging is exploited
to resolve the mean time evolution of the flow and the signal from a single
constant temperature hot wire probe is employed as phasing reference. The
flow-field information obtained from visualizations agrees well with
quantitative indications provided by measures, and the comparison allows to
precisely understand what information can be extracted from simple
visualizations. As a result, new insight in flow mechanism is obtained from the
analysis of the flow data showing that, for the analyzed plate distance, the
gap between the two plates behaves substantially as a cavity while the vortex
formation process takes place in the wake region behind the aft plate.