Morphology and flow behavior of buoyant bubble plumes

•Lagrangian tracking of captured bubbles to obtain the morphology and flow behavior•Bubble coalescence found to be more dominant than bubble breakup•A novel correlation proposed to estimate the bubble shape by accounting all forces•Current correlation applicable for a wider range of bubble sizes than existing ones The morphological and hydrodynamic behavior of bubbles in air–water plumes was studied by employing Particle Tracking Velocimetry (PTV) techniques. Individual bubbles were identified by analyzing the instantaneous high-speed camera images of the plume. The bubble velocities were then obtained by Lagrangian tracking of each bubble, based on its size and location. The nature of bubble coalescence and breakup was also investigated based on the change in the projected area of the parent and daughter bubbles. The effect of the bubble position and the air inflow rate on the bubble properties like diameter, aspect ratio, velocity, number flux, etc., and on the coalescence and breakup behavior was investigated. A novel correlation is proposed to estimate the bubble aspect ratio as a function of bubble Reynolds number and Eotvos number, for a wide range of flow conditions, and is compared with existing correlation from the literature.