Direct Measurement of the Viscocapillary Lift Force near a Liquid Interface

Area of Science:

• Fluid dynamics
• Soft matter physics
• Interfacial phenomena

Background:

• Lift forces are crucial in various scientific fields, including mechanics and biology.
• Understanding forces at liquid-liquid interfaces is essential for many applications.
• Previous studies have not directly measured lift forces on particles at such interfaces.

Purpose of the Study:

• To directly measure the lift force acting on a particle moving along a liquid-liquid interface.
• To investigate the relationship between particle proximity to the interface and lift force magnitude.
• To validate theoretical models with experimental data.

Main Methods:

• Direct experimental measurement of lift force using specialized apparatus.
• Particle motion simulation in a viscous fluid at a two-liquid interface.
• Application of soft lubrication theory for modeling and numerical calculations.

Main Results:

• The lift force was directly measured for the first time on a particle at a liquid-liquid interface.
• Lift force increases as the particle-interface distance decreases.
• Force reaches a saturation point at very small distances from the interface.

Conclusions:

• The study provides the first direct experimental evidence of viscous lift forces at liquid-liquid interfaces.
• Experimental results align well with theoretical predictions from soft lubrication theory.
• The findings offer insights into particle behavior and fluid dynamics in multiphase systems.