Direct numerical simulation of bubble-induced turbulence. (11th May 2021)

• Record Type: Journal Article
• Authors: Innocenti, Alessio; Jaccod, Alice; Popinet, Stéphane; Chibbaro, Sergio
• Is Part Of: Journal of fluid mechanics. Volume 918(2021)
• Publication Date: 2021-05-11
• Subjects: bubble dynamics, -- gas/liquid flow; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2021.288
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract: Abstract : We report on an investigation of bubble-induced turbulence. Bubbles of a size larger than the dissipative scale cannot be treated as pointwise inclusions, and generate important hydrodynamic fields in the carrier fluid when in motion. Furthermore, bubble motions may induce a collective agitation due to hydrodynamic interactions which display some turbulent-like features. We tackle this complex phenomenon numerically, performing direct numerical simulations with a volume-of-fluid method. In the first part of the work, we perform both two-dimensional and three-dimensional tests in order to determine appropriate numerical and physical parameters. We then carry out a highly resolved simulation of a three-dimensional bubble column, with a set-up and physical parameters similar to those used in laboratory experiments. This is the largest simulation attempted for such a configuration and is only possible thanks to adaptive grid refinement. Results are compared both with experiments and previous coarse-mesh numerical simulations. In particular, the one-point probability density function of the velocity fluctuations is in good agreement with experiments. The spectra of the kinetic energy show a clear $k^{-3}$ scaling. The mechanisms underlying the energy transfer and notably the possible presence of a cascade are unveiled by a local scale-by-scale analysis in physical space. The comparison with previous simulations indicates to what extent simulations not fully resolved may yet give correct results, from a statistical point of view.