Computational Fluid Dynamics Simulation of Generation and Coalescence of Bubbles in Non-Newtonian Fluids

摘要

The successive generation and coalescence behaviors of bubbles from two parallel nozzles in non-Newtonian fluids were numerically simulated by using the volume of fluid (VOF) method. Three flow patterns for bubbles and the related flow regime transition lines were obtained. Two critical nozzle intervals exist: one for the bubble coalescence before pinch-off, and another for alternating bubble formation then in-line coalescence under different conditions. Two correlations were proposed to predict the dimensionless critical nozzle intervals for the transition of bubble-flow patterns. The influences of nozzle diameter, gas flow rate, nozzle interval, and rheological properties of fluid on bubble-flow patterns were investigated systematically.