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 f raction specification to track the movement of the gas-liquid interfac e. The terminal speed of the bubbles is well predicted for 10 less tha n or equal to Eo less than or equal to 100 and 10(-12)less than or equ al 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 w all. The shape of the trailing edge is flat in some cases and an oblat e spheroid in other cases. A criterion of Fr>0.3 seems to be appropria te 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.