Removal of particles from holes in submerged plates with oscillating bubbles

Abstract

This study is motivated by a common problem in submerged tubes and structures, which is the blockage of the tubes by pollutant particles or debris from the surrounding fluid. To clear the obstruction from the tube, an expanding bubble is used to propel the obstruction away from the tube (the tube is represented as a submerged transparent plate with a hole in our experiments). In some cases the obstruction removal effect is reinforced by the impacting jet of such a collapsing bubble. The bubble is generated via a simple low voltage electric spark discharge circuit. The pressure generated by the oscillating bubble effectively pushes the particle away from the tube, thereby successfully clearing the obstruction. High-speed photography is used to record and analyze the phenomenon. The speed of the particle is found to be around 1 m/s shortly after the collapse of the bubble. Interestingly, there is a clear difference between air-backed plates and water-backed plates in terms of bubble and particle dynamics. The bubbles in the current study are typically of millimeter size. Since the physics are similar for smaller bubbles, the process can possibly be downsized for other microapplications such as the removal of blood clots in vessels [S. R. Visuri et al., U.S. Patent No. 6428531 (August 6, 2002)].