CFD Modeling of Gas-Liquid Bubbly Flow in Horizontal Pipes: Influence of Bubble Coalescence and Breakup

Abstract

Modelling of gas-liquid bubbly flows is achieved by coupling a population balance equation with the three-dimensional, two-fluid, hydrodynamic model. For gas-liquid bubbly flows, an average bubble number density transport equation has been incorporated in the CFD code CFX 5.7 to describe the temporal and spatial evolution of the gas bubbles population. The coalescence and breakage effects of the gas bubbles are modeled. The coalescence by the random collision driven by turbulence and wake entrainment is considered, while for bubble breakage, the impact of turbulent eddies is considered. Local spatial variations of the gas volume fraction, interfacial area concentration, Sauter mean bubble diameter, and liquid velocity are compared against experimental data in a horizontal pipe, covering a range of gas (0.25 to 1.34 m/s) and liquid (3.74 to 5.1 m/s) superficial velocities and average volume fractions (4% to 21%). The predicted local variations are in good agreement with the experimental measurements reported in the literature. Furthermore, the development of the flow pattern was examined at three different axial locations ofL/D= 25, 148, and 253. The first location is close to the entrance region where the flow is still developing, while the second and the third represent nearly fully developed bubbly flow patterns.

Computational fluid dynamic model for the estimation of coke formation and gas generation inside petrochemical furnace pipes with the use of a kinetic net

“…The liquid and gas flow together, exchanging momentum and energy, forming a nearly asymmetric profile distribution for the superficial velocities. Similar profiles can be observed in the works of Fontoura et al, [11] Yeoha et al, [21] and Ekambara et al [22][23] A slight, nearly unnoticeable increase in the asymmetry of the superficial liquid velocity distribution is observed in Figure 4. Even though the geometry is symmetric, the two-phase flow is never symmetric and it only reaches a pseudo-steady state.…”

A novel drag force coefficient model for gas–water two-phase flows under different flow patterns

“…According to the former studies, it was well known that the lift force depends on bubble diameter, fluid properties and flow conditions (Zun, 1980;Auton, 1987;Drew and Lahey, 1987;Lance and Lopez de Bertodano, 1994;Ekambara et al, 2012). The lift force coefficient can be modeled with or without considering the bubble deformation, i.e.…”

“…How to simulate and model all of the flow patterns is really a challenge. Although following the advantage of computer technology, the flow structure and specific physical parameters in two-phase flows can be numerically simulated based on computational fluid dynamics (CFD) methodology (Zhang et al, 2006;Ustinenko et al, 2008;Ekambara et al, 2012), as well known, the accuracy of CFD will depend on the models (Sanyal et al, 1999;Lain et al, 2002;Krepper et al, 2009;Yuan et al, 2011). At moment there is no one model which can deal with all of the flow patterns for CFD.…”

Modelling strategies for emulsification in industrial practice

“…Coupled CFD-PBM for dispersed flow with droplet/bubble break-up and coalescence has been developed quite far by now for pipe flow [16] and other fairly simple but industrially relevant geometries, like hydrocyclones [17] and stirred vessels. [5] However, we are not aware of successful applications to food-type emulsions in complex rotor-stator devices.…”