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Counter‐rotating vortex shedding generated by acoustic excitations in confined mixing layers
Author(s) -
Zhao Wei,
Wang Guiren
Publication year - 2019
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16577
Subject(s) - vorticity , vortex , mixing (physics) , vortex shedding , mechanics , particle image velocimetry , particle (ecology) , radius , strouhal number , mathematics , physics , reynolds number , turbulence , geology , oceanography , computer security , quantum mechanics , computer science
Abstract Ultrafast mixing enhancement has been realized in confined mixing layers at an optimal forcing frequency, under which the flow exhibits the strongest mixing. The fast mixing is accompanied by the so‐called counter‐rotating vortices (CRVs). In this investigation, by using particle imaging velocimetry (PIV) and laser‐induced fluorescence, the conditions of generating CRVs in confined mixing layers are theoretically and experimentally investigated. To generate CRVs, (a) the acoustic particle displacement must be larger than the summation of the curvature radius of the trailing edge and the thickness of the Stokes layer, and (b) the temporal derivative term of the vorticity equation should be larger than the convective term of the mean vorticity generated by the mean flow. This study enhances our understanding on vortex shedding dynamics and enables novel designs of fast mixers for continuous operations in process industry.