Three-Dimensional Volume of Fluid Simulations of Air Bubble Dynamics in a Converging Nozzle

The present work relates to the dynamics of single bubbles accelerating through a converging nozzle. There are two main aspects to this study. First, this expands upon a previously used two-dimensional model [1] by providing three-dimensional volume of fluid (VOF) simulations that show better agreement with experiments. The VOF model is employed to perform simulations using the commercial computational fluid dynamics (CFD) code ANSYS FLUENT. Second, the present work uses experimental high-speed camera results in conjunction with simulation results to demonstrate bubble time trace and velocity information. Time series of the average liquid velocity at the atomizer exit orifice when the bubble exits as determined via simulation are reported. The passing of a bubble through the nozzle is found to cause a significant fluctuation in the exit velocity that is coupled to the liquid and gas dynamics upstream of the exit.