Liquid bubble

Abstract: Direct numerical simulations of bubbly flows are reviewed and recent progress is discussed. Simulations, of homogeneous bubble distribution in fully periodic domains at relatively low Reynolds numbers have already yielded considerable insight into the dynamics of such flows. Many aspects of the evolution converge rapidly with the size of the systems and results for the rise velocity, the velocity fluctuations, as well as the average relative orientation of bubble pairs have been obtained. The challenge now is to examine bubbles at higher Reynolds numbers, bubbles in channels and confined geometry, and bubble interactions with turbulent flows. We briefly review numerical methods used for direct numerical simulations of multiphase flows, with a particular emphasis on methods that use the so-called "one-field" formulation of the governing equations, and then discuss studies of bubbles in periodic domains, along with recent work on wobbly bubbles, bubbles in laminar and turbulent channel flows, and bubble formation in boiling.

Abstract: The formation of gas bubbles and their subsequent rise due to buoyancy are very important fundamental phenomena that contribute significantly to the hydrodynamics in gas−liquid reactors. The rise o...

Abstract: Shock wave emission and cavitation bubble expansion after optical breakdown in water with Nd:YAG laser pulses of 30‐ps and 6‐ns duration is investigated for energies between 50 μJ and 10 mJ which are often used for intraocular laser surgery. Time‐resolved photography is applied to measure the position of the shock front and the bubble wall as a function of time. The photographs are used to determine the shock front and bubble wall velocity as well as the shock wave pressure as a function of time or position. Calculations of the bubble formation and shock wave emission are performed using the Gilmore model of cavitation bubble dynamics and the Kirkwood–Bethe hypothesis. The calculations are based on the laser pulse duration, the size of the plasma, and the maximally expanded cavitation bubble, i.e., on easily measurable parameters. They yield the dynamics of the bubble wall, the pressure evolution inside the bubble, and pressure profiles in the surrounding liquid at fixed times after the start of the laser...