Shape-Morphing Dynamics of Soft Compliant Membranes for Drag and Turbulence Modulation

TL;DR

This study investigates how soft, compliant membranes deform and influence turbulence and drag in fluid flows, revealing nonlinear behaviors and the potential for flow control through membrane dynamics.

Contribution

It introduces a nonlinear aeroelastic model for membrane deformation and demonstrates how membrane oscillations can modulate turbulence and drag in fluid flows.

Findings

Membranes deform into parachute-like shapes at higher flow velocities.

Membrane oscillations can trigger turbulence production in the wake.

The nonlinear model accurately predicts membrane deformation and force fluctuations.

Abstract

We study the kinematics and dynamics of a highly compliant membrane disk placed head-on in a uniform flow. With increasing flow velocity, the membrane deforms nonlinearly into increasingly parachute-like shapes. These aerodynamically elongated materials exhibit a modified drag law, which is linked to the elastohydrodynamic interactions. We predict the unsteady structural response of the membranes using a nonlinear, aeroelastic model -- in excellent agreement with experimental measurements of deformations and force fluctuations. With simultaneous membrane interface tracking, force measurements and flow tracing, we reveal that a peculiar skewness in the membrane's oscillations triggers turbulence production in the wake, thereby modulating the drag. The present work provides a demonstration of the complex interplay between soft materials and fluid turbulence, leading to new, emergent system properties.