Numerical simulation of bubble rising behavior in a tannin-based foaming precursor resin

Area of Science:

• Materials Science
• Fluid Dynamics
• Chemical Engineering

Background:

• Understanding bubble dynamics is crucial for optimizing foaming processes in materials like tannin-based resins.
• The behavior of bubbles, including their rise, deformation, and coalescence, is influenced by fluid properties and initial conditions.

Purpose of the Study:

• To develop and utilize a two-dimensional volume of fluid (VOF) model to simulate bubble deformation, rise velocity, distance, and trajectory.
• To investigate the impact of resin properties (viscosity, surface tension) and bubble characteristics (initial radius, location) on bubble behavior.
• To analyze the coalescence of parallel and coaxial double bubbles in the resin.

Main Methods:

• Development of a two-dimensional volume of fluid (VOF) model.
• Simulation of single and double bubble (parallel and coaxial) dynamics in a tannin-based foaming precursor resin.
• Systematic variation of resin viscosity, surface tension, initial bubble radius, location, and inter-bubble distance.

Main Results:

• Increased resin viscosity led to decreased bubble rising velocity and lower flow rate.
• Elevated surface tension impeded bubble shape deformation.
• Larger initial bubble radius resulted in faster rising velocity.
• For parallel double bubbles, symmetry and vortex interactions influenced their divergence and merger.
• For coaxial double bubbles, closer proximity and larger radii accelerated fusion time.

Conclusions:

• Bubble dynamics in tannin-based resins are significantly affected by fluid viscosity, surface tension, and bubble size.
• Inter-bubble distance critically influences coalescence behavior in both parallel and coaxial configurations.
• The findings provide insights into controlling bubble growth rates during the foaming process.