Experimental observation of flow instability control by metamaterial subsurfaces

TL;DR

This study demonstrates a passive, energy-efficient flow control method using phononic metamaterials embedded beneath surfaces to suppress vortex instabilities, reducing turbulence and drag without altering surface texture.

Contribution

The paper introduces a novel passive flow control technique employing phononic metamaterials to suppress vortex instabilities without surface modifications.

Findings

Metamaterials can suppress vortex growth at specific frequencies.

Passive control reduces flow turbulence and drag.

Experimental validation confirms effectiveness of the approach.

Abstract

Flow instabilities within a fluid flow can cause laminar-to-turbulent transition over surfaces. These instabilities can result from upstream, wake-generating disturbances, leading to increased drag and turbulence-induced energy losses. Flow control strategies can address these issues through active methods, requiring energy input, or passive systems, which operate without added input. Here, we present a passive approach to flow control using embedded phononic metamaterials to alter vortex instability development, without changing the outer-surface's texture, roughness or compliance. Experiments confirm that our subsurface can suppress vortex growth at target frequencies, demonstrating the potential for energy-efficient flow management with phononic subsurfaces.