Numerical study of an individual bubble rise in a shear-thinning viscoelastic liquid based on a combination of the Carreau and FENE-CR models

The rise behavior of a single bubble in shear-thinning viscoelastic liquids was investigated using a volume of fluid method based on a combination of the Carreau and FENE-CR models. The effects of Weissenberg number (Wi), polymer stretching parameter (L), Eötvös number (Eo) and rheological index (n) on bubble shape and typical characteristics of flow fields were investigated in detail. The results show that bubble tail becomes pointed under the influence of elastic stress, and the bubble becomes longer along the longitudinal direction with a decrease in Wi. When the magnitude of n is relatively large, the bubble appears as an ellipsoidal shape with a cusp; however, when the magnitude of n is relatively small, bubble shape is closer to a disc, and the tip of bubble tail disappears. Wi affects the magnitude of elastic tensile stress, and affects the action rang of the large tensile stress. With an increase in Wi, the action rang of elastic tensile stress develops from both sides of the bubble towards regions below bubble tail. The appearance of negative wake is not directly related to bubble shape, but to the relaxation of elastic stres.