Isolated bubble ascent in a non-Newtonian media inside an infinite bubble column: a CFD study

Bubble columns are widely used as multiphase contacting devices in chemical process industries (CPIs), wherein, the gas–liquid interaction is very crucial. The rheological behavior of the liquid phase shifts from Newtonian (NF) to non-Newtonian (n-NF) during the process in CPIs that alters the bubble dynamics inside the bubble column at the local level which further contributes to modifying the global hydrodynamics parameters i.e., gas holdup, regime transitions, mixing time, and mass transfer. In order to understand this complex phenomenon, an isolated bubble was simulated inside an infinite domain in the presence of water (a low-viscosity NF) and CarboxyMethyl Cellulose (CMC) (a shear-thinning n-NF). Simulations were performed ANSYS Fluent 19.2 using the Volume of Fluid (VOF) model to capture/track bubble interface along with the Continuum Surface Force (CSF) model to treat surface tension. The CFD results of terminal velocity were validated with the experimental measurement and correlation’s prediction for bubble ascent in conventional bubble columns. The validated CFD model effectively demonstrated the terminal velocity, bubble shape, trajectory, molecular viscosity, strain rate and bubble–liquid dynamic behavior. There is a limited research comparing bubble behavior in both NF and n-NF. This study significantly contributes by comparing the unique bubble behavior and dynamics in these fluids. The findings of this study will provide a useful guideline for designing and development of diverse gas–liquid contacting devices.