Comparison among drag coefficient models of single bubbles under high and low Morton number regimes

Bubble dynamics analysis is highly dependent on drag coefficient computation, and several models have been proposed to compute it. The present study reviewed some of the correlations for the drag coefficient evaluation, and aims to compare the most successfull models available and how they fit the experimental data, spanning over several orders of Morton number regimes (-10.6 <= log(10)M <= 0.6), including bubbles with different geometrical shapes: spherical, ellipsoidals and cap-like bubbles. The present study categorized the correlations based on their dependency on the aspect ratio. The aspect ratio-dependent models showed great results for E > 0.5, whereas for large departures from sphericity, the independent models fit well the experimental data. To tackle the shortcomings found in these models, a new hybrid correlation was proposed that showed a good compatibility with the experimental results for log(10)M <= -1.5, 0.1 <= E-o <= 100 and 1 <= Re <= 2000 with a maximum average difference from the experimental values for bubble terminal velocity and aspect ratio within respectively 10% and 15%. (C) 2021 Elsevier Ltd. All rights reserved.