Bubble viscosity effect on internal circulation within the bubble rising due to buoyancy using the level set method

► The pressure field is calculated in addition to the velocity components. ► A level-set method has been applied to trace the interface. ► The internal circulation increases as the viscosity-ratio of the phases increase. ► Mass conservation was investigated with greater accuracy. In this article, the effect of bubble viscosity on internal circulation within a bubble has been analyzed numerically. The Finite Volume Method and SIMPLE algorithm have been used for field solution. This algorithm calculates the pressure field in addition to the velocity components that do not appear in related literature. A level-set method has been applied for tracking the interface between the bubble and the fluid around it. The solution algorithm was first validated for a parasitic flow. Then, the bubble shape deformation was simulated for bubbles with different Eotvos and Morton numbers, and the results were compared with experimental findings. Comparison of the results is encouraging. It is concluded that the internal circulation intensity increases as the viscosity-ratio between the bubble and the fluid around it increases. In this research, mass conservation was investigated with greater accuracy than that of previous studies using the level set method.