Fast-freezing kinetics inside a droplet impacting on a cold surface.

Area of Science:

• Physics
• Materials Science
• Fluid Dynamics

Background:

• Droplet solidification is crucial in natural phenomena and industrial processes like inkjet printing and chip manufacturing.
• Understanding droplet freezing kinetics is essential for optimizing various technological applications.

Purpose of the Study:

• To elucidate the freezing kinetics during droplet impact on an undercooled surface using total-internal reflection (TIR).
• To investigate the peculiar freezing morphology and self-peeling phenomenon observed during droplet solidification.

Main Methods:

• Utilized total-internal reflection (TIR) as an optical technique to observe droplet freezing.
• Combined classical nucleation theory with large-scale hydrodynamics to analyze the solidification process.

Main Results:

• Observed a unique freezing morphology with sequential advection of frozen fronts from the droplet center to boundaries at high undercooling.
• Reported a self-peeling phenomenon of the frozen splat, driven by a transient crystalline state during solidification.

Conclusions:

• The study successfully elucidates droplet freezing kinetics by integrating nucleation theory and hydrodynamics.
• The findings offer insights into droplet solidification mechanisms, relevant for industrial applications.