Weakly coupled fluid-structure interaction between wall-bounded turbulent flows and defect-embedded phononic subsurfaces

TL;DR

This study explores how defect-embedded phononic subsurfaces interact with turbulent flows, revealing a frequency-selective mechanism that can modify turbulence and reduce drag through passive resonance effects.

Contribution

It introduces a weakly coupled fluid-structure framework to analyze turbulence-phononic surface interactions, demonstrating unique frequency shifts and turbulence modifications.

Findings

D-Psub exhibits a narrow-band response despite broadband turbulence

Coupled system shows a shift in dominant oscillation frequency due to fluid-structure interaction

Passive resonant surfaces can filter and reorganize turbulent energy for flow control

Abstract

We investigate the interaction between wall-bounded turbulence and defect-embedded phononic subsurface (D-Psub) using a weakly coupled fluid--structure framework, in which the flow and structure are advanced sequentially without sub-iterations. The D-Psub subsurface is modeled as a dynamic wall with a resonance introduced via a localized structural defect, driven by spatially averaged wall-pressure fluctuations from a turbulent channel flow. This configuration enables a controlled study of how a narrow-band structural response interacts with the broadband forcing of near-wall turbulence. Despite broadband turbulent forcing, the D-Psub exhibits a narrow-band response that modifies near-wall dynamics, with representative cases showing suppression of velocity fluctuations, increased coherence of streamwise streaks, and a measurable reduction in turbulent drag. Crucially, the coupled system displays behavior that cannot be replicated by prescribed wall motion: the dominant oscillation frequency shifts away from the designed resonance due to fluid--structure interaction. Additionally, the phase between panels is shown to be governed by the convection of turbulent structures. These results reveal a mechanism by which phononic subsurfaces filter and reorganize turbulent energy through frequency-selective coupling, distinct from conventional compliant or actively forced walls. The findings provide a physical basis for designing passive resonant surfaces that exploit turbulence-structure coupling for flow control.