Eur. Phys. J. B 38, 127-138 (2004)
https://doi.org/10.1140/epjb/e2004-00108-y

Vortex dynamics around a solid ripple in an oscillatory flow

¹ The Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark
² Cornell University, Department of Theoretical and Applied Mechanics, Ithaca, NY 14853, USA
³ The Technical University of Denmark, Department of Physics, 2800 Kgs. Lyngby, Denmark

Corresponding author: ^a apa9@cornell.edu

Received: 23 October 2003
Revised: 6 January 2004
Published online: 20 April 2004

Abstract

We investigate the time-dependent flow of water around a solid triangular profile oscillating horizontally in a narrow rectangular container. The flow is quasi two-dimensional and using particle image velocimetry we measure 20 snapshots of the entire velocity field during a period of oscillation. From the velocity measurements we obtain the circulation of the vortices and study the vortex dynamics. The time-dependence of the flow gives rise to the formation of a jet-like flow structure which enhances the vorticity production compared to the time-independent case. We introduce a simple phenomenological model to describe the important dynamical parameters of the flow, i.e., the vortex circulation and the jet velocity. We solve the model analytically without viscous damping and find good agreement between the model predictions and our measurements. Our work adds to the recent effort to understand more complicated flows past sand-ripples and insect wings.