A numerical model of Taylor bubbles rising through stagnant liquids in vertical tubes

The motion of large bubbles in tubes is investigated numerically-with a two-dimensional, transient, finite difference model using a volume fraction specification to track the movement of the gas-liquid interface. The terminal speed of the bubbles is well predicted for 10 less than or equal to Eo less than or equal to 100 and 10(-12)less than or equal to Mo less than or equal to 10(1). The ubiquitous prolate spheroid leading edge is predicted. Both viscosity-dominated equilibrium films and essentially inviscid accelerating films are observed on the tube wall. The shape of the trailing edge is flat in some cases and an oblate spheroid in other cases. A criterion of Fr>0.3 seems to be appropriate to ensure a flat bottom on the bubble. Some favourable comparisons are made with detailed velocity profile measurements available in the literature. (C) 1998 Elsevier Science Ltd. All rights reserved.