Utilization of Cavity Vortex To Delay the Wetting Transition in One-Dimensional Structured Microchannels

Area of Science:

• Fluid dynamics
• Surface science
• Materials science

Background:

• Frictional resistance is linked to liquid-gas interface slip.
• Delaying wetting transitions is crucial for managing surface friction.
• Understanding liquid-gas interface dynamics is key to controlling wetting phenomena.

Purpose of the Study:

• To investigate cavity shape manipulation for delaying wetting transitions.
• To explore the role of liquid-driven vortices in energy dissipation.
• To identify optimal cavity geometries for enhanced surface performance.

Main Methods:

• Fabrication of polydimethylsiloxane microchannels with side-wall cavities.
• Experimental visualization and analysis of liquid-gas interface dynamics.
• Numerical simulations to corroborate experimental findings.
• Testing of various cavity shapes (square, trapezoidal, U-shape).

Main Results:

• Two distinct flow regimes identified: protruding interface and wetting transitions.
• Trapezoidal cavities demonstrated superior performance in delaying wetting transitions compared to vertical-walled cavities.
• Inclined cavity walls were found to exert greater force on the liquid-gas interface, delaying wetting.
• Liquid-driven vortices were confirmed to play a role in energy dissipation.

Conclusions:

• Cavity geometry significantly influences wetting transition dynamics.
• Trapezoidal cavities offer an effective passive strategy for delaying wetting transitions.
• The proposed method presents a promising alternative to active control methods for reducing friction.