Numerical modeling of the free rise of an air bubble

Abstract

The results of a numerical investigation of the dynamics of a single air bubble rising in water are presented. The bubbles, 1, 2.5, 3, 5, 8, and 10 mm in diameter, are considered. An analysis is based on the numerical solution of the complete three-dimensional system of Navier–Stokes equations for a two-phase medium using an implicit approach with the automatic tracking of the gas-water interface by means of separating the volume fractions. Emphasis is placed on an examination of the local physical characteristics of the motion. The calculated mean rise velocities are compared with experimental data. The rising bubble trajectories are shown to be periodic, zigzag or helical in shape, which is due to the variation in their form and the generation of a characteristic turbulent wake behind them. The bubble rise velocities are correlated with the forces acting on the bubbles.