Large-Scale Turbulent Pressure Fluctuations Revealed by Ned Kahn's Artwork

We investigate the dynamics of pendulum chains immersed in turbulent boundary layers. We combine laboratory experiments and video analysis of the kinetic facade exhibits by the artist Ned Kahn, composed of large-scale clusters of centimeter-sized plates oscillating freely in the wind. At the laboratory scale, we show that a one-dimensional pendulum chain immersed in a wind tunnel exhibits a wave dispersion relation derived from a Sine-Gordon equation. Under the wind action, the dynamical response is either dominated by a resonance phenomenon, or a linear response to pressure fluctuations. From amateur video analysis on large-scale kinetic facades, we show that the plate oscillation is driven by the same resonant response mechanisms and the apparent wavy pattern corresponds to the most energetic Fourier mode propagating at the advection speed of pressure fluctuations.