Liquid Fraction Effect on Foam Flow through a Local Obstacle.

Area of Science:

• Fluid Dynamics
• Materials Science
• Soft Matter Physics

Background:

• Quasi-two-dimensional liquid foams are complex fluids with applications in various industries.
• Understanding foam rheology and flow behavior is crucial for process optimization and material design.
• Previous studies have explored foam dynamics, but the interplay of liquid fraction and confinement effects requires further investigation.

Purpose of the Study:

• To experimentally investigate the rheological properties and flow patterns of quasi-two-dimensional liquid foams.
• To analyze the impact of varying liquid fractions and obstacle geometries on foam velocity and permeability.
• To introduce and validate a simplified method for estimating foam liquid fraction.

Main Methods:

• Experiments were conducted using a Hele-Shaw cell with a central permeable obstacle.
• Foam velocity was quantified using a standard cross-correlation algorithm.
• Liquid fraction was estimated via a novel statistical analysis of foam cell structures.

Main Results:

• Foam velocity fields exhibited distinct patterns that varied with increasing liquid fraction.
• The rheology of the foam showed significant changes correlated with liquid fraction.
• Local permeability decreased as obstacle height and liquid fraction increased.
• At high liquid fractions (5.8×10-2), permeability approached zero when obstacles occupied over 78% of the cell gap.

Conclusions:

• Liquid fraction and obstacle geometry are critical parameters governing foam flow and rheology in confined geometries.
• The developed simplified method provides a viable approach for liquid fraction estimation in foams.
• The findings offer insights into the behavior of foams under varying conditions, relevant for industrial applications.