How microstructures affect air film dynamics prior to drop impact.

Area of Science:

• Fluid Dynamics
• Surface Science
• Nanotechnology

Background:

• Liquid drop impact on surfaces can create a dimple due to air pressure buildup.
• Understanding this phenomenon is crucial for applications involving liquid-solid interactions.

Purpose of the Study:

• To measure air layer profiles under impacting drops on hydrophobic micropatterned surfaces.
• To investigate the influence of micropillar spacing and height on air dimple evolution.

Main Methods:

• Employed high-speed color interferometry.
• Studied millimeter-sized drops impacting surfaces at approximately 0.4 m/s.
• Analyzed the effects of varying micropillar dimensions.

Main Results:

• Decreased micropillar spacing led to an increased air dimple height.
• The air-droplet interface deformed between pillars before complete wetting.
• Larger pillar heights increased deformation but minimally affected dimple height.

Conclusions:

• Micropattern geometry significantly influences air layer dynamics during drop impact.
• Findings provide insights into controlling liquid behavior on textured surfaces.