Bubbling from Submerged Twin-Orifices and a Simplified Model

Abstract

Air bubbles were generated from twin orifices submerged in water. Bubbling features were observed using high-speed video and the micro convection induced by the generating bubble was detected at each orifice by a hot wire anemometer. It is found that bubbling pattern differs depending on the chamber volume as well as the air volumetric flow rate. When the chamber volume is small and the flow rate is relatively low, different patterns of “reciprocal” and “counterpart” bubbling appear repeatedly with the change of flow rate. Between the two patterns, “aperiodic” bubbling takes place. To reveal the mechanism of such interactive bubbling, a simplified dynamic model is proposed, which describes the time evolution of bubbles' volumes basing on the equations of motion for gas and liquid. The distribution of air flow rate to twin orifices is governed by the effects of surface tention and inertia of water flow around the growing twin bubbles. The model explains well the appearance of three bubbling patterns and their repetition.