Dynamics of two-dimensional bubbles

Area of Science:

• Fluid Dynamics
• Computational Physics

Background:

• Understanding bubble dynamics is crucial in various multiphase flow applications.
• Buoyancy-driven motion of bubbles is influenced by forces like surface tension, viscosity, and drag.

Purpose of the Study:

• To numerically investigate the dynamics of two-dimensional bubbles ascending due to buoyant forces.
• To characterize bubble trajectories, shapes, and terminal velocities using dimensionless numbers.

Main Methods:

• Employed a one-fluid model coupled with the front-tracking technique for numerical simulation.
• Analyzed bubble dynamics by recording position, shape, and orientation over time.
• Utilized Eötvos, Archimedes, and Reynolds numbers to describe bubble behavior.

Main Results:

• At low Reynolds numbers, bubbles followed straight paths with steady wakes.
• At high Reynolds numbers, bubbles exhibited periodic zigzag trajectories and unstable wakes resembling the Von Karman vortex street.
• Numerical results showed good qualitative agreement with experimental observations in Hele-Shaw cells.

Conclusions:

• The study successfully models bubble dynamics, capturing phenomena like zigzag motion and vortex streets.
• Numerical calculations provide a good approximation of bubble dynamics, especially for larger gaps in Hele-Shaw cells.
• Dimensionless numbers effectively describe the qualitative properties and terminal velocities of ascending bubbles.