Supercooled water drops impacting superhydrophobic textures.

Area of Science:

• Materials Science
• Fluid Dynamics
• Surface Chemistry

Background:

• Understanding water-surface interactions is crucial for anti-icing strategies.
• Supercooled water's behavior on superhydrophobic textures is not fully understood.

Purpose of the Study:

• Investigate supercooled water drop impact on superhydrophobic surfaces.
• Analyze the influence of viscous effects on impact dynamics and icing potential.

Main Methods:

• Experimental investigation of supercooled water drops impacting superhydrophobic textures.
• Varying drop supercooling down to -17 °C.
• Analysis of impact dynamics, spreading, recoil, and meniscus behavior.

Main Results:

• Increased viscosity in supercooled water reduces maximum spreading by ~25%.
• Contact time doubles under supercooling due to decreased recoil speed.
• Meniscus penetration occurs centrally, not in a ring shape.
• Superhydrophobicity breakdown occurs at higher velocities (~3.5 m/s) without bubble entrapment.
• Viscous effects can prevent rebound even with partial texture penetration.

Conclusions:

• Viscous effects significantly alter supercooled water drop impact dynamics on superhydrophobic surfaces.
• These effects have critical implications for water retention, rebound, and icing.
• A novel mechanism for superhydrophobicity breakdown under supercooled conditions is identified.