Interfacial Area Transport Equation for Bubble Coalescence and Breakup: Developments and Comparisons

Area of Science:

• Multiphase Flow Dynamics
• Fluid Mechanics
• Chemical Engineering

Background:

• Bubble coalescence and breakup are critical phenomena in various physical-chemical processes.
• The Interfacial Area Transport Equation (IATE) is a key tool for modeling these processes, often treating bubbles in two groups.
• Understanding these interactions is vital for accurately predicting fluid behavior in reactors, pipelines, and other industrial applications.

Purpose of the Study:

• To provide a comprehensive review of IATE models for bubble coalescence and breakup.
• To analyze five distinct bubble interaction mechanisms: random collision, wake entrainment, turbulent impact, shearing-off, and surface instability.
• To identify limitations and suggest future research directions for enhancing IATE's predictive capabilities.

Main Methods:

• Review and synthesis of existing literature on IATE for bubble dynamics.
• Analysis of one-group and two-group IATE constitutive models.
• Evaluation of bubble interaction mechanisms and their governing parameters.
• Discussion of experimental challenges in interface measurement.

Main Results:

• Bubble size, velocity, and collision frequency are dominant in coalescence.
• Turbulent kinetic energy and inertial force combined form an effective criterion for bubble breakup.
• Existing models often neglect viscous shear, shearing-off, and surface instability effects in breakup.
• Two-group IATE performance is sensitive to channel geometry; models for various channel types are summarized.

Conclusions:

• Significant progress has been made in extending IATE beyond bubbly flow to churn-annual flow.
• Challenges remain in modeling highly distorted interfaces and experimental measurements.
• Further research is needed to address IATE's general applicability limitations and improve constitutive models.