Abstract
The importance of air bubble dynamics in liquid is in some phenomena like chemical and biochemical processes in refinery units. The 2D Volume of Fluid (VOF) method together with the CFD technique were employed for simulating. The dynamic meshing technique is used to simulate the hydrodynamics of rising air bubble in liquid water column via the User Defined Function (UDF) code in the C++ environment was developed to evaluate bubble rising through the water column. The rising of air bubble through a stagnant water column has been considered and the influence of column dimension, bubble size, and aspect ratio on the rising velocity characterized is investigated. The obtained results showed that the bubble rising velocity increase with the bubble size and its shapes was transformed from ellipsoidalto-ellipsoidal cap shape. The rising velocity of air bubbles was affected by the column diameter. It was observed that the air bubble moving toward the top of the water column with oscillation for all cases. A good agreement was obtained between the rising velocity predicted in the simulation with that obtained from the literature.
Highlights
The phenomenon of air-water two-phase flow appeared in many applications such as in petroleum, chemical, nuclear power plant, solar energy, and biogas energy [1,2,3,4]
The air bubble rising through the water column has been considered and the impact of column dimension, bubble size, and aspect ratio on the rising velocity and shapes of the air bubble is investigated
The computational fluid dynamics (CFD) results of a single air bubble rising through a water column with different bubble sizes of are depicted in Figure (3)
Summary
The phenomenon of air-water two-phase flow appeared in many applications such as in petroleum, chemical, nuclear power plant, solar energy, and biogas energy [1,2,3,4]. The motion of air bubbles in a liquid column can be considered very complex because of the high viscosity and density ratios. Many numerical techniques and computing power were advanced like computational fluid dynamics (CFD) which became a good approach of studying the behavior of rising air bubble in vertical water column [7,8,9,10]. Chen et al [25] used the method of the volume of fluid to simulate the rising of a single bubble in a stagnant water column and the interaction of the gas-water interface. Kishor et al [28] presented a numerical simulation of bubble hydrodynamic and pressure drop due to friction associated with gas-liquid two-phase flow in T-junction microchannel. Zhang et al [29] experimentally investigated the transient motion of a single bubble in a highly viscous fluid, they successfully provided empirical correlations for total drag coefficient and joint unsteady force coefficient which are in very good agreement with the experimental results
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