Dynamics of a cavitation bubble between oblique plates

Abstract

Experiments were performed to investigate the collapse dynamics of a cavitating bubble generated between a pair of symmetrically arranged oblique plates. A 2.0 mm gap was left at the converging end of the two plates, which were inclined at an angle of 10°. A focused laser beam generated a cavitation bubble of about 4.0 mm in diameter, at four different locations that were placed on the centerline between the glass plates. A high-speed camera captured the bubble's cavitating dynamics at a frame rate of 75 kHz. The initial position of the bubble and, thus, the boundary conditions significantly influenced the bubble's dynamics. The bubble's first collapses showed a distinct unidirectional extended jetting but without notch formation on the bubble's left surface. Subsequent collapses led to intense nucleation, a feature useful in microfluidic devices. Further on, we observed vertical pillar-shaped cavities, floating toroids, etc., shapes that were rarely mentioned in previous investigations. To support our experimental results, we performed numerical simulations based on solving the Navier–Stokes equations, to replicate similar bubble dynamics. Our results provided insight into bubble dynamics generated between oblique plates, thereby potentially contributing to an improved understanding of microfluidic pumping techniques, surface cleaning devices, fouling of complex shapes, biomedical devices employing cavitation-based methods, and micromixing of fluids. Results of these experiments may serve also as benchmark data to validate numerical methods.