2018/11/09 by Andre Weiner, Weiner, Andre, Jens Timmermann +11 · 1 citation
Engineering · Environmental Science · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Mixing #Minerals Flotation and Separation Techniques #Particle Dynamics in Fluid Flows
paper · pdf · doi:10.48550/arxiv.1811.03851
openalex publication_date 2018/11/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this article, we present experimental and numerical techniques to\ninvestigate the transfer, transport, and reaction of a chemical species in the\nvicinity of rising bubbles. In the experiment, single oxygen bubbles of\ndiameter d b = 0.55 . . . 0.85 mm are released into a measurement cell filled\nwith tap water. The oxygen dissolves and reacts with sulfite to sulfate.\nLaser-induced fluorescence is used to visualize the oxygen concentration in the\nbubble wake from which the global mass transfer coefficient can be calculated.\nThe ruthenium-based fluorescent dye seems to be surface active, such that the\nrise velocity is reduced by up to 50 % compared to the experiment without\nfluorescent dye and a recirculation zone forms in the bubble wake. To access\nthe local mass transfer at the interface, we perform complementary numerical\nsimulations. Since the fluorescence tracer is essential for the experimental\nmethod, the effect of surface contamination is also considered in the\nsimulation. We employ several improvements in the experimental and numerical\nprocedures which allow for a quantitative comparison (locally and globally).\nRise velocity and mass transfer coefficient agree within a few percents between\nexperiment, simulation and literature results. Because the fluorescence tracer\nis frequently used in mass transfer experiments, we discuss its potential\nsurface activity.\n