Solitary bubbles rising in quiescent liquids: A critical assessment of experimental data and high-fidelity numerical simulations, and performance evaluation of selected prediction methods

Bubbles are ubiquitous in industrial applications and in the natural environment. The dynamics of solitary bubbles rising through quiescent liquids, in particular, underpins the physics of two-phase bubbly flows, which are commonplace in industrial, biological, and environmental flows. This review provides a critical assessment of experimental data and high-fidelity numerical simulations concerning the rise of solitary bubbles in quiescent liquids, and an evaluation of selected prediction methods for the rise velocity and the aspect ratio of the bubbles. The assessment of the experimental data is performed by way of a large and diversified bubble rise data bank collected from the literature (7192 data points from 58 literature studies), which is critically analyzed dedicating special attention to various aspects that have not been adequately addressed in previous investigations, including the methodologies employed to generate the bubbles, the techniques adopted to measure their size, shape, and rise velocity, the consequence of the liquid contamination on the bubble dynamics, wall-confinement effects, and the mass transfer between the bubble and the surrounding liquid. The assessment of the computational studies covers direct numerical simulations with interface capturing, interface tracking methods, and linear stability analyses, which are critically analyzed with specific focus on numerical methods, computational mesh, validation vs experimental data, and their main findings. The evaluation of the prediction methods is restricted to selected and widely quoted methodologies, three for the bubble rise velocity and four for the bubble aspect ratio, which have been proposed for final applications and whose performance is assessed against the measured data. The curated bubble rise data bank is provided in full and usable form. Research gaps and topics that necessitate further investigation are identified and discussed.