Self-Lifting Droplet Driven by the Solidification-Induced Solutal Marangoni Flow

Area of Science:

• Physics
• Fluid Dynamics
• Materials Science

Background:

• Multicomponent droplets are crucial for applications like 3D printing, electronics, and medical diagnostics.
• Droplet transformations and morphologies are often driven by evaporation-induced flow and phase transitions.

Purpose of the Study:

• To investigate the self-lifting behavior of frozen binary droplets.
• To understand the underlying physicochemical hydrodynamics driving this counterintuitive phenomenon.

Main Methods:

• Experimental observation of droplet self-lifting.
• Theoretical analysis incorporating solidification front propagation.
• Quantitative elucidation of physical parameter effects on self-lifting.

Main Results:

• Demonstrated self-lifting of frozen binary droplets, nearly doubling their height against gravity.
• Identified internal solutal Marangoni flow, reaching speeds up to 1 mm/s, as the driving mechanism.
• Achieved excellent agreement between theoretical predictions and experimental results for droplet shape evolution.

Conclusions:

• The study attributes droplet self-lifting to solutal Marangoni flow driven by solute concentration gradients at the solidification front.
• Provides quantitative understanding and guidance for controlling self-lifting behavior.
• Advances knowledge of hydrodynamics in phase-changing multicomponent liquid systems for technological applications.