Dynamics of Bubbles Rising in Pseudo-2D Bubble Column: Effect of Confinement and Inertia

Abstract

Thin rectangular bubble columns, or pseudo-2D configurations, are widely used in experimental studies of bubble dynamics as a simplified geometry that allows optical access to bubble behaviour. This numerical study examines the dynamics of bubbles (5–7 mm diameter, Re ≈ 1000–2000) rising in pseudo-2D configurations with varying gap sizes between confining parallel plates.

The results reveal that most bubbles adopt an oblate spheroidal shape with chaotic rise behaviour, exhibiting continual fluctuations in aspect ratio, orientation, and velocity. Bubble aspect ratio generally decreases with increased confinement. At higher Reynolds numbers (D = 7 mm, h/D = 1), bubbles display more elongated oblate spheroidal shapes and predominantly rectilinear rise behaviour, attributed to severe disruption of toroidal vortex formation at the confining walls. Smaller gap sizes inhibit vortex formation at wall surfaces and confine hairpin vortex structures toward the bubble’s side interface, preventing large-scale path oscillations and limiting fluctuations to high-frequency behaviour. A region of recirculating flow forms in the wake from rapid vortex detachment. These findings provide mechanistic insight into the role of confinement in pseudo-2D systems and have implications for the interpretation of experimental bubble column data.

@article{gumulya2021dynamics,
  title         = {Dynamics of Bubbles Rising in Pseudo-2D Bubble Column: Effect of Confinement
                  and Inertia},
  author        = {Gumulya, M and Utikar, Ranjeet P and Pareek, Vishnu K and Evans, Geoffrey M
                  and Joshi, Jyeshtharaj B},
  year          = 2021,
  journal       = {Chemical Engineering Journal},
  publisher     = {Elsevier},
  volume        = 405,
  pages         = 126615,
  doi           = {10.1016/j.cej.2020.126615}
}