Hypergyrating Droplets Generated on a Selective Laser-Textured Heterogeneous Wettability Surface

Area of Science:

• Surface Science and Engineering
• Fluid Dynamics
• Materials Science

Background:

• Droplet impact on surfaces involves spreading, retraction, and bouncing.
• Spontaneous droplet gyrating is an interesting phenomenon with potential applications.
• Existing methods for droplet gyrating lack efficiency and speed.

Purpose of the Study:

• To present an ultrahigh-speed gyrating droplet generation method.
• To investigate torque transmission on heterogeneous wettability surfaces for droplet gyrating.
• To explore applications in energy transformation and cleaning strategies.

Main Methods:

• Fabrication of hybrid superhydrophobic-superhydrophilic (SH-SHL) patterns on aluminum alloy substrates using selective laser texturing.
• Characterization of surface wettability, including static, advancing, and receding contact angles.
• Experimental analysis of droplet impact dynamics on patterned surfaces coupled with substrate rotation.

Main Results:

• Achieved hypergyrating speeds exceeding 96,700 rpm, significantly higher than previous reports.
• Demonstrated a high energy transformation ratio (α) of 83.40% from substrate torque to droplet gyrating energy.
• Showcased control over maximum gyrating speed by adjusting pattern size and substrate driving speed.

Conclusions:

• The hybrid SH-SHL patterned surface effectively converts impact and rotational energy into hypergyrating droplet motion.
• The developed method offers a practical approach for energy transformation and advanced cleaning strategies.
• This technique holds promise for various industrial applications requiring controlled high-speed droplet manipulation.