The Role of Orifice Shape in Controlling Bubble Growth and Interface Stability

Understanding the mechanisms of interface formation and bubble growth at submerged orifices is essential for a wide range of engineering applications. Of particular interest here are the design and operation of gas diffusion electrodes for organic electrosynthesis. While the Young-Laplace equation can accurately describe interface shapes and Laplace pressures for circular orifices under quasi-static conditions, no simplified models exist for non-circular geometries or dynamic environments. To address this gap, we employ phase-field simulations based on the coupled Cahn-Hilliard–Navier-Stokes equations to investigate the wetting behavior and the process of bubble growth at differently shaped orifices under potentially dynamic conditions. We systematically vary the orifice shape as well as wetting conditions and show the significant influence of these parameters on the interface morphology and the Laplace pressure at different stages of bubble growth. Additionally, we examine the impact of crossflow and pulsating conditions on the stability of the gas-liquid interface. Based on our simulation results, we provide physical explanations of the observed phenomena. Our findings demonstrate that tailored orifice design can enhance the stability of gas-liquid interfaces and proves to be a way of controlling bubble formation dynamics.