Bubble formation and dynamics in a quiescent high‐density liquid

Abstract

Gas bubble formation from a submerged orifice under constant-flow conditions in a quiescent high-density liquid metal, lead-bismuth eutectic (LBE), at high Reynolds numbers was investigated numerically. The numerical simulation was carried out using a coupled level-set and volume-of-fluid method governed by axisymmetric Navier-Stokes equations. The ratio of liquid density to gas density for the system of interest was about 15,261. The bubble formation regimes varied from quasi-static to inertia-dominated and the different bubbling regimes such as period-1 and period-2 with pairing and coalescence were described. The volume of the detached bubble was evaluated for various Weber numbers, We, at a given Bond number, Bo, with Reynolds number Re ) 1. It was found that at high values of the Weber number, the computed detached bubble volumes approached a 3/5 power law. The different bubbling regimes were identified quantitatively from the time evolution of the growing bubble volume at the orifice. It was shown that the growing volume of two consecutive bubbles in the period-2 bubbling regime was not the same whereas it was the same for the period-1 bubbling regime. The influence of grid resolution on the transition from period-1 to period-2 with pairing and coalescence bubbling regimes was investigated. It was observed that the transition is extremely sensitive to the grid size. The transition of period-1 and period-2 with pairing and coalescence is shown on a Weber-Bond numbers map. The critical value of Weber number signalling the transition from period-1 to period-2 with pairing and coalescence decreases with Bond number as We $ Bo 21 , which is shown to be consistent with the scaling arguments. Furthermore, comparisons of the dynamics of bubble formation and bubble coalescence in LBE and water systems are discussed. It was found that in a high Reynolds number bubble formation regime, a difference exists in the transition from period-1 to period-2 with pairing and coalescence between the bubbles formed in water and the bubbles formed in LBE. V C 2015 American Institute of Chemical Engineers AIChE J, 61: 3996-4012, 2015

The Formation Behavior of a Single Bubble in Power-Law Fluids

“…Xie et al (2012) experimentally investigated the formation and detachment of the bubbles generated from an immersed micro-orifice on a plate in a stagnant and isothermal liquid. In addition to the experimental investigation, many researchers are dedicated to simulating the process of bubble formation by the direct numerical simulation (DNS) technique with prosperous computational methodology (Gerlach et al, 2007;Ma et al, 2012;Albdawi et al 2003;Wielhorski et al, 2014;Zahedi et al, 2014;Islam et al, 2015;Chakraborty et al 2015).…”

Continuous formation of microbubbles during partial coalescence of bubbles from a submerged capillary nozzle

“…Bubble formation and coalescence are widely encountered in the chemical process industry, petrochemical industry and mineral processing 1‐3 . As the bubble size decreases, its surface area for a given gas volume increases and its residence time in liquid becomes longer.…”

Numerical Simulation of Quasi-Static Bubble Formation from a Submerged Orifice by the Axisymmetric VOSET Method

“…Buwa et al (2007) and Gerlach et al (2007) used CLSVOF method to investigate the periodic bubble formation and analyze the transition of single period to double period. Similarly, periodic bubble formation in high-density liquid was also investigated by Chakraborty et al (2015) using the CLSVOF method. And, the same numerical method was also used to study the quasi-static bubble formation by Albadawi et al (2013).…”