Interaction of Sustained Vortex Shedding with a Phononic Subsurface: Effect of Positioning and Resonant Characteristics

Abstract: Phononic materials (PMs) have emerged as a promising candidate to passively and beneficially interact with unsteady flows. However, their fluid–structure interaction (FSI) with separated flows exhibiting sustained periodic vortex shedding remains completely unexplored. In this study, we use a high-fidelity immersed boundary method to systematically investigate the strongly coupled, nonlinear FSI dynamics of vortex shedding from a fully separated flow over a flat plate that exhibits sustained periodic vortex shedding, with an embedded PM subsurface (PSub) modeled as a grounded diatomic chain driving a compliant section on the flat plate. We probe the dependence of the coupled system dynamics on two parameters: (1) the PSub chordwise position, which sets its spatial relationship to the surrounding flow structure, and (2) the rate of growth of the resonant displacement amplitude of a PSub, a behavioral parameter identified as a key driving parameter in PSub interaction with latent vortex shedding in prior work. Simulation results show that these two parameters drive clear and systematic changes to the limit-cycle vortex shedding. The PSub chordwise position determines the limit cycle PM–FSI dynamics, which can be classified into four distinct regimes as a function of position, ranging from substantial amplification to strong attenuation of the lift and drag oscillation amplitudes in the limit cycle. Results reveal a configuration that reduces lift oscillation amplitude by over 30\% and drag oscillation amplitude by over 50\% with less than 0.5\% change in mean lift and drag. Displacement amplitude envelope primarily governs the transient responsiveness toward the limit cycle, where its influence on the limit cycle also depends on the chordwise position. We analyze the characteristic frequencies, phase relationship between the PSub’s displacement and the lift, and unsteady and mean flow fields of the vortex-shedding process to explain the mechanisms by which the PM modifies the flow.

Citation: S. Park, V. Ramakrishnan, A. M. Burgos, A. Goza, K. H. Matlack, "Interaction of Sustained Vortex Shedding with a Phononic Subsurface: Effect of Positioning and Resonant Characteristics", Under Review, 2026