Influence of the Initial Shape of a Bubble on Bubble Rise Dynamics in a Stagnant Viscous Fluid

The effect of the shape of a single bubble at the initial instant on the bubble rising dynamics in a viscous fluid at rest is studied. Elliptical bubbles with various compression ratios are considered. Mathematical simulation of the process is based on the volume of fluid method, which makes it possible to trace the evolution of the interface. The results of calculations of test problems are in adequate agreement with the data of other authors available in the literature. The shapes of the interfacial surface and the velocity and vorticity fields in the process of bubbles rising in the gravity field are obtained at the Reynolds number Re = 35 and the Bond numbers Bo = 10 and 125. The main attention is paid to the regime of unsteady motion. It is shown that the bubble rise velocity has one or two local maxima depending on the properties of the media. It is found that bubbles initially elongated vertically rise more rapidly than those elongated horizontally.