Dynamics of an isolated bubble injected at the horizontal wall in a shear flow
Phys. Rev. Fluids 10, 123603 – Published 18 December, 2025
DOI: https://doi.org/10.1103/xn86-fg3p
Abstract
The quasistatic growth of a bubble in a shear flow is investigated. Experiments are performed in a horizontal rectangular channel with air bubbles growing in water. The bubbles are generated on the bottom wall of the channel on two substrates (glass and treated glass) with different wetting conditions. During its growth and detachment, the bubble is recorded with high-speed video camera allowing the measurements of several geometric parameters. These parameters are then used to evaluate the static and hydrodynamic forces acting on the bubble. On the glass substrate, the bubble foot expands outside the injection cavity as the liquid flow rate increases, resulting in an elongation of the bubble foot, while on the treated glass substrate, the bubble foot remains almost constant at a value close to injection cavity radius. Using the force balance acting on the bubble allows us to determine the drag coefficient of the bubble versus the bubble Reynolds number, which is well predicted by expression deduced from numerical simulation by Shi et al. [Phys. Rev. Fluids 5, 073601 (2020)]. Furthermore the theoretical expressions for the drag and lift forces by Shi et al. [Phys. Rev. Fluids 5, 073601 (2020)] allows us to verify the force balance throughout the bubble growth with an error less than . Using these theoretical expressions with the experimental observation that the detachment occurs when the advancing (upstream) contact angle reaches a critical value depending on the surface wettability, allows us to build a new criteria for the bubble detachment that is in good agreement with the measurement.
