A NUMERICAL-MODEL OF SLUG FLOW IN VERTICAL TUBES

This paper presents a numerical method for the determination of the fl ow field structure in slug flow in vertical tubes. The method is based on the ensemble averaged transport equations governing the Bow of the liquid around the Taylor bubble and in the slug, which together compr ise one slug unit. Turbulence is accounted for by the k-epsilon model. An iterative scheme is used to compute the shape and velocity of the Taylor bubble simultaneously with the flow field; the conditions which are taken to determine these quantities are uniform bubble pressure a nd smoothness of the bubble nose. The equations are discretised using a finite volume technique on a block structured, non-orthogonal mesh w hich conforms to the Bow domain boundary. The predicted velocities of a single Taylor bubble rising in both stagnant and moving liquid agree very well with experimental data. For a train of Taylor bubbles in pe riodic slug flow, the computed bubble rise velocity and pressure gradi ent agree well with the data provided that account is taken of the pre sence of dispersed gas in the liquid slug. (C) 1997 Elsevier Science L td.