Author, as appears in the article.: Fard, Mojtaba Goraki; Vernet, Anton; Stiriba, Youssef; Grau, Xavier
Department: Enginyeria Mecànica
URV's Author/s: Grau Vidal, Francesc Xavier / Stiriba, Youssef / Vernet Peña, Antonio
Keywords: Vortex Turbulence Regime transitions Numerical-simulation Model Liquid velocity Large-scale structures Large-eddy-simulation Large-eddy simulation Gas-distribution Dynamics Conditional sampling Cfd simulation Bubble column reactor Behavior
Abstract: This paper analyses the local and time-dependent behavior of large-scale structures responsible for liquid circulation in gas-water flow of a 3-D cylindrical bubble column of high aspect ratio with a multiple orifice for uniform aeration. The large-scale flow structures play an important role in the mixing and the mass transfer while coherent structures dominate hydrodynamic characteristics of the turbulent flow field. A three-dimensional Euler-Euler large eddy simulation (LES) model was used to calculate large-scale structures and their interaction with bubbles at inlet superficial gas velocities of U-G = 6 and 8.4 cm/s where vortical-spiral and turbulent flow regimes occur. The two-phase model gives good agreements with experimental measurements. We use a conditional sampling procedure of liquid velocity and gas hold-up time series to identify and educe the development of coherent flow structures which consists in a pair of counter-rotating vortices convected in a staggered pattern along the column in both the vortical-spiral and central plume regions. On average, the detected instantaneous events for each template account for about 12-15% of the data recorded and may appear simultaneously. These events produce important fluctuations in the axial liquid velocity and gas void fraction. The sampling procedure yielded the averaged topology of the three-dimensional large-scale structures which was visualized using isosurfaces of the vorticity for different gas flow rates. The structures have spiral tube-shaped topology rotating along the column near the walls with a pair of counter-rotating cells sustained through the flow. This work provides deep insights into turbulent flow field in gas-liquid bubble column by LES and pattern recognition. (C) 2020 Published by Elsevier Ltd.
Thematic Areas: Physics and astronomy (miscellaneous) Physics and astronomy (all) Mechanics Mechanical engineering Matemática / probabilidade e estatística General physics and astronomy Fluid flow and transfer processes Engenharias iv Engenharias iii Engenharias ii Ciência de alimentos Ciência da computação Biodiversidade
licence for use: https://creativecommons.org/licenses/by/3.0/es/
ISSN: 03019322
Author's mail: youssef.stiriba@urv.cat anton.vernet@urv.cat francescxavier.grau@urv.cat
Author identifier: 0000-0002-0272-7807 0000-0002-7028-1368 0000-0002-4077-7338
Record's date: 2024-10-12
Papper version: info:eu-repo/semantics/acceptedVersion
Link to the original source: https://www.sciencedirect.com/science/article/abs/pii/S0301932219306196
Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
Papper original source: International Journal Of Multiphase Flow. 127 (UNSP 103236): 103236-
APA: Fard, Mojtaba Goraki; Vernet, Anton; Stiriba, Youssef; Grau, Xavier (2020). Transient large-scale two-phase flow structures in a 3D bubble column reactor. International Journal Of Multiphase Flow, 127(UNSP 103236), 103236-. DOI: 10.1016/j.ijmultiphaseflow.2020.103236
Article's DOI: 10.1016/j.ijmultiphaseflow.2020.103236
Entity: Universitat Rovira i Virgili
Journal publication year: 2020
Publication Type: Journal Publications