Control of Vortical Structures by Bimodal Excitation in a Two-Dimensional Jet

Abstract

Coherent vortex structure was controlled by bimodal excitation in a two-dimensional jet. The scale of the symmetrical vortex structure was different in the nonlinear interference region. The growth of the subharmonic component was increased remarkably for Φ_<in>=0°, 300°, Φ_<in> is the phase difference between Strohal frequency and the subharmonic frequency. In the meantime, it was suppressed for Φ_<in>=120°. For Φ_<in>=300°, the vortex was merged until X/2H ≒8 in the excited intensity of ±1%, and until X/2H ≒6 in the excited intensity of ±2%. After the pairing, the vortex arrangement became anti-symmetric. The pairing of the vortex was not regularly generated for Φ_<in>=120°.