Wake Patterns Behind a Flapping Foil

We study in this work the different kind of patterns which develop in the wake of a flapping foil. The system which makes the foil flap is simple and consists of two pulleys and a motor. The Strouhal number St (associated with the foil frequency) and the Reynolds number Re (associated with the flow velocity) can be continuously varied; the oscillation amplitude \(A_{D}\) can take two values. We localize the regions of existence of the different patterns in the planes (\(St, A_{D}\)) and (Re, St). We conclude that for 140\(\,< Re <\,\)320, the generated structures do not depend upon the Reynolds number.