Topological variations in the optimal vortex due to the interaction of two concentric synthetic jets

Abstract

Synthetic jets are devices that periodically generate a vortex producing thrust, which is similar to the vortex driving the swimming motion of some marine animals (i.e.: jellyfish, squids, …). The optimal working conditions of these devices lead to the artificial generation of a vortex that maximizes thrust and efficiency, known as the optimal vortex. This article shows the topological variations of the optimal vortex produced by the periodic interaction of an external concentric jet over the jet main stream. For such aim, numerical simulations have been carried out at three different working conditions, generating three types of vortices, representing the artificial generation of (i) vortices producing small quantity of thrust but requiring low energetic supplies (sub-critical conditions), (ii) vortices producing large quantity of thrust but requiring high energetic supplies (super-critical conditions) and (iii) the optimal vortex producing maximum thrust using minimal energetic supplies. Topological variations will determine the effect produced by the interaction of the external concentric jet with the three types of vortices described above. Keywords: Synthetic jet, Optimal vortex, Concentric jets, Flow topology