An Imploding Circular Water Wave

When a heavy solid object, such as a rock, impacts a fluid surface, like a lake, a crater is created and subsequently begins to pinch radially inward, resulting in the vertical water jets we call ripples.

In this image, the dynamics of an imploding circular water wave are simulated experimentally using a simple gate-type water table and high-speed video imaging. A circular, converging water wave is created by rapidly retracting a gate separating a region of high water level from a region with lower water level. Four cylindrical obstacles are placed in the path of the collapsing wave to test the stability of the imploding wave.

The figure shows a sample snapshot of this implosion process just before the wave breaks at the center, visualized from the bottom of the water table. The center of convergence of the water wave coincides with the center of symmetry of the implosion. The transient, inward-sweeping turbulent flow created by the retracting gate, as well as the outward-sweeping trajectory of the disturbances on the water wave caused by the four cylindrical obstacles, can be seen and traced.

Image credit: A. Shchetinina & H.D. Ng (Concordia University, Montréal, Canada) Snapshot of an imploding circular water wave with four cylindrical obstacles in its path

This image was an award winner at the Gallery of Fluid Motion at the 64th APS Division of Fluid Dynamics Annual Meeting, in November 2011.
  2011 Gallery of Fluid Motion

This research was performed by Anna Shchetinina and Hoi Dick Ng, Department of Mechanical and Industrial Engineering, Concordia University, Montréal, Canada. Research is funded by the Natural Sciences and Engineering Research Council of Canada.