Subharmonic Resonance in a Shear Layer
The initiation, growth, interaction, breakdown and regeneration of coherent structures in turbulent shear flows are the manifestations of a hierarchy of flow instability mechanisms. After the initial roll up of the shed vortex sheet into discrete vortices, the most common interaction that a shear layer undergoes is pairing of two neighboring vortices. The pairing process, i.e. the growth of the subharmonic, is a consequence of what has come to be known as subharmonic resonance -- the nonlinear interaction between a wave of frequency f and a subharmonic wave of frequency f/2, producing an f/2 component which is capable of reinforcing the subharmonic. Such reinforcement depends on excitation parameters such as the phase between the fundamental and the subharmonic, and the critical fundamental amplitude[1, 2].
KeywordsShear Layer Flow Visualization Strouhal Number Exit Plane Subharmonic Resonance
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