Measurement of the velocity field in parametrically excited solitary waves

• Published in: Journal of fluid mechanics Vol. 754; pp. 590 - 604
• Main Authors: Gordillo, Leonardo, Mujica, Nicolás
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 10.09.2014
• Subjects: Accuracy; Boundary layers; Computational fluid dynamics; Exact sciences and technology; Excitation; Flow velocity; Fluid dynamics; Fluid flow; Fluid mechanics; Free surfaces; Fundamental areas of phenomenology (including applications); Hydrodynamic waves; Hydrodynamics; Mathematical models; Numerical analysis; Physics; Propagation; Solitary waves; Vibration; Walls; solitary waves; parametric instability; waves/free-surface flows; Solitary wave; Parametric instabilities; Test facilities; Vibration effect; Free surface flow; Particle image velocimetry; Experimental study; Velocity measurement
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/jfm.2014.416

Parametrically excited solitary waves emerge as localized structures in high-aspect-ratio free surfaces subject to vertical vibrations. Herein, we provide the first experimental characterization of the hydrodynamics of these waves using particle image velocimetry. We show that the underlying velocity field of parametrically excited solitary waves is primarily composed of a subharmonic oscillatory component. Our results confirm the accuracy of Hamiltonian models with added dissipation in describing this field. Remarkably, our measurements also uncover the onset of a streaming velocity field which we show to be as important as other crucial nonlinear terms in the current theory. Using vorticity equations, we show that the streaming pattern arises from the coupling of the potential bulk flow with the oscillating boundary layers on the vertical walls. Numerical simulations provide good agreement between this model and experiments.