This presentation will focus on three aspects of so-called Taylor bubbles, large volumes of gas rising in vertical tubes. In the first part a method is demonstrated which permits to considerably accelerate the rise velocity of Taylor bubbles by inserting coaxially with the tube a “cage” of equally spaced vertical rods. The physical principle of the phenomenon is explained and the results demonstrated numerically. The presentation then turns to the blow-out phenomenon responsible for many disasters in off-shore drilling such as the Deepwater Horizon Macondo blow-out in the Gulf of Mexico in 2010. The mechanism underlying these phenomena is explained in physical terms supported by numerical simulations based on the drift-flux model. Finally, the instability of the axial symmetry of Taylor bubbles in a vertical tube when exposed to a liquid downflow is considered and the role of the Rayleigh-Taylor instability in the process elucidated.
About the Speaker
Following his departure from the Johns Hopkins University after several decades of service as C.A. Miller Jr. Professor of Mechanical Engineering, Andrea Prosperetti is currently a Distinguished Professor of Mechanical Engineering at the University of Houston, with a part-time appointment as Berkhoff Professor of Applied Physics at the University of Twente in the Netherlands. Prosperetti’s scientific interests center on multiphase flow, with a particular focus on bubble dynamics, averaged equations and resolved simulations of particular focus on bubble dynamics, averaged equations and resolved simulations of particulate flows. He has authored/co-authored over 250 journal paper and two books. He is an elected member of the National Academy of Engineering.