Computations of Upward Water/Air Fluid Flow in Vertical Pipes

Abstract

In the present paper, a numerical code has been developed with different turbulence models aiming at simulating turbulent bubbly flows in vertical circular pipes. The mass and momentum conservation equations are used to describe the motion of both phases (water/air). Because of the averaging process additional models are needed for the interphase momentum transfer and turbulence quantities for closure. The continuous phase (water) turbulence is represented using different turbulence models namely: two-equation k-?, extended k-? and shear-stress transport (SST) k-? turbulence models which contains additional term to account for the effect of the dispersed phase (air) on the continuous phase turbulence. The developed code is based on the finite volume method with the mentioned different turbulence models. The Reynolds stresses of the dispersed phase are calculated by relating them to those of the continuous phase through a turbulence response function. The code has been tested through two different cases: the prediction of air/water bubbly flow in a vertical pipe and bubbly flow in a sudden enlargement pipe where phase fractions, velocity profiles and turbulence can be compared with available experimental data. It is concluded that, SST k-? produces the best validations in view with the other turbulence models and the comparisons with other simulations and experimental data from literature.