The motion and shape of a bubble in highly viscous liquid flowing through an orifice

Abstract

Experiments and theory concern the behaviour of a small bubble carried through an orifice by a very viscous liquid. The liquid was polybutene oil, of viscosity about 70 Pa s, i.e. 70,000 times that of water. The Reynolds number of the flow is substantially less than one, hence the flow pattern is approximately radial flowing into, and away from, the orifice. These flow patterns have profound effects on the shape of an entrained bubble. On the upstream side, the acceleration of the liquid, as it approaches the orifice, causes elongation of the bubble since the front of the bubble moves faster than the back. On the downstream side, the reverse occurs: the back of the bubble moves fast than the front. Thus the height of the bubble diminishes as it moves away from the orifice, leading to the formation of a 'crescentmoon' shape. The shape of these bubbles can be predicted by considering the motion of a droplet of the same liquid replacing the bubble: the resulting geometric theory gives good predictions of bubble deformation approaching the orifice and of 'crescent-moon' formation downstream of the orifice.

Effects of surface topography on low Reynolds number droplet/bubble flow through a constricted passage

“…In addition to elongation, some interesting shapes have also been observed through a rectangular constriction for a smaller drop size and higher velocities. Chen et al [40] observed crescent moon shaped bubbles coming out of a rectangular constriction (Fig. 6).…”

Effects of Nozzle Structure on Bubble Deformation and Coalescence in Quiescent Liquid

“…The interaction of multiple bubbles rising in a liquid is a fundamental aspect in understanding bubble column hydrodynamics . Bubble formation from submerged nozzles/orifices over a wide range of gas flow rates, − nozzle/orifice configuration, − surface wetting characteristics, − and the physical properties of the dispersed and continuous phases − have been extensively studied in the past decades. In particular, the formation of bubbles that grow quasistatically from a submerged injector inside an initially quiescent liquid has been the most studied configuration due to its simplicity and importance in many engineering applications.…”

The influence of water hardness perturbations on bubble departure dynamics

“…The process of gas bubble formation in liquids has been investigated since the 1950s. These studies included investigations into bubble formation in bubble-beds and foam beds 1 ; experiments to determine the effects of factors such as liquid surface tension, liquid viscosity, liquid density, and gas-flow rates on bubble size 2 – 4 ; and the application of results from chaos theory to understand the dynamics of the bubble departure process 5 – 7 . Because the chaotic nature of the gas bubble departure process is influenced by many factors, some presently unknown, these studies continue.…”