Investigation of instability in the dynamic behaviour of a bubble

Abstract

In order to obtain the laws of the bubble's dynamic behaviours, the interFoam solver in OpenFOAM was used to simulate the bubbles, and the experimental device was built to prove the reliability of the results. The Eötvös number (Eo) and the Galileo number (Ga) were used to classify the bubbles into four regions according to their different dynamic behaviours: straight line without deformation region, slight zigzag without deformation region, zigzag with slight deformation region, and zigzag with strong deformation region. Eo of bubbles in the straight line without deformation region is extremely small and is greatly influenced by surface tension. The bubbles do not deform and rise linearly along the axis of symmetry. Eo of bubbles in the slight zigzag without deformation region is still small and the bubbles do not deform, but the path is curved for a period of time. As the value of Eo increases, the bubble in the zigzag with the slight deformation region is weakened. The path is a regular zigzag, and the axisymmetric structure of the bubbles is destroyed. In the zigzag with the strong deformation region, the values of Eo and Ga are large. The path amplitude increases and the periodic law is broken. The bubble's deformation and vortex shedding interact with each other, both of which are the causes of the bubble's path instability.