Vortex simulation of artificial control of mixing layers

A numerical experiment is performed to control vortex motion and the growth of 2D, spatially-growing mixing layers. Multiple-frequency forcing is applied and the flow field is analyzed using a vortex method. Forcing is prescribed as a superposition of a fundamental frequency with its subharmonics. Superposition up to three frequencies is considered. The effects of phase shift between forcing frequencies and the relative amplitude ratio are also examined. Results show that the number of merging vortices, patterns of vortex merging, positions of vortex merging, and thus the growth of a mixing layer can be effectively controlled by multiple-frequency forcing, if forcing frequencies, phase shift and amplitude ratio are suitably selected.