General power-law temporal scaling for unequal-size microbubble coalescence

Area of Science:

• Fluid dynamics
• Microfluidics
• Computational physics

Background:

• Microbubble coalescence is crucial in various applications.
• Understanding the influence of liquid properties (viscosity, density, surface tension) is key.
• Previous studies lack a generalized scaling law for microbubble coalescence.

Purpose of the Study:

• To systematically investigate the impact of liquid viscosity, density, and surface tension on microbubble coalescence.
• To develop a general power-law temporal scaling for microbubble coalescence time.
• To provide insights for optimizing microfluidic systems.

Main Methods:

• Lattice Boltzmann simulation for microbubble coalescence.
• Characterization using the Ohnesorge number (Oh).
• Extensive simulations (138 cases) with GPU parallelization and validation.

Main Results:

• A general power-law temporal scaling T*=A₀γ⁻ⁿ was derived and validated.
• The prefactor A₀ is linear to Ohnesorge number (Oh).
• The power index n varies linearly with Oh for Oh<0.66 and becomes constant for Oh>0.66.

Conclusions:

• The derived scaling law accurately predicts microbubble coalescence time based on size inequality.
• Liquid properties significantly influence coalescence dynamics.
• Findings offer valuable guidance for microfluidic system design and optimization.