Boundary layer transition induced by low-speed synthetic jets

The effect of low-speed, circular synthetic jets (SJ) on the turbulent transition a laminar boundary layer is studied through direct numerical simulations. SJ capability in fixating streamwise location onset analyzed terms its operation parameters (reduced frequency F + and momentum coefficient [Formula: see text]). free-stream turbulence (FST) near-wall vortical structures generated by jet as well, to mimic actual control system. Velocity spectra, phase portraits, dynamic mode decomposition allow us investigate flow unsteadiness chaotic state. In most investigated cases, SJs successfully promote transition, result varicose-symmetric hairpin-like vortices at exits. particular, it found that increasing always reduces size region; non-monotonic behavior fetch noted reduced increased, suggesting existence an optimal value. Combination FST actuation results spanwise-asymmetric structures, with little difference compared previous case. present analysis can be used gather information practical implementation low-speed actuators active turbulators.