The dynamics of a bubble in the internal fluid flow of a pipeline

Abstract

In the aeronautical and marine engineering fields, bubbles are often carried in the pipelines of filling systems and marine risers. Under the action of internal flow, air bubbles seriously threaten device security. Therefore, to analyze the motion and deformation of a bubble in the internal fluid flow of a pipeline, we establish a corresponding boundary element numerical model based on the potential flow theory. A comparison of the numerical model results with the experimental results verifies the accuracy of the model. Subsequently, we simulate the dynamics of a bubble under the action of the internal flow, and the influence of the velocity, pipe radius, and surface tension on the bubble movement are discussed. When the dimensionless flow velocity exceeds 0.3, the bubbles will be seriously deformed. Different flow velocity directions cause different deformations of the annular bubbles in the later stages. Additionally, the channel limits bubble deformation. If the pipe radius is greater than 5, the effect of the pipe on the bubble is negligible. We also find that surface tension keeps the bubbles morphologically stable under internal flow. When the surface tension coefficient exceeds 2.45 × 10−4, it will not make the bubble toroidal.