Numerical Simulations of a Train of Air Bubbles Rising Through Stagnant Water
Transient numerical simulations of the rise of a train of gas bubbles in a liquid are presented. Computational Fluid Dynamics is used to simulate the axisymmetric two-dimensional flow in and around a set of bubbles separated by a fixed distance. The homogeneous multiphase model available in CFX was used. This model allows the simulation of the flow inside and outside the bubble with no additional empirical correlations for drag or slip velocity. The effect of surface tension is included through a continuous surface model by Brackbill et al. Three bubble diameters were considered: 1 mm, 5mm and 40 mm. The first bubble is expected to maintain a spherical shape, the second is expected to become elliptical and the third is in the range of the spherical cap regime. The CFX results showed that the predicted bubble shape agreed well with data from Clift et al. Terminal velocity as well as flow patterns and bubble shape are compared to available data.