Drop impact and capture on a thin flexible fiber.

Area of Science:

• Fluid dynamics
• Materials science
• Surface science

Background:

• Understanding droplet-fiber interactions is crucial in various applications, including microfluidics and material coating.
• The dynamics of droplet impact and capture on flexible structures are complex and depend on multiple physical parameters.

Purpose of the Study:

• To investigate the capture dynamics of inviscid and viscous drops impacting flexible fibers.
• To characterize the influence of fiber flexibility, viscosity, and impact speed on droplet capture and fracture.
• To identify the optimal fiber parameters for maximizing droplet capture efficiency.

Main Methods:

• Theoretical analysis of droplet-fiber impact dynamics.
• Characterization of drop thread elongation and fiber deformation.
• Analysis of the interplay between fiber bending timescales and drop deformation timescales.

Main Results:

• Droplet capture is favored by larger fiber elasticity and slower bending times, allowing the fiber to recoil after drop recoil.
• When fiber bending and drop deformation timescales are comparable, drop capture is less prevalent due to premature fiber rebound.
• In the limit of highly flexible fibers, capture efficiency is determined by the momentum transfer during impact.

Conclusions:

• Fiber rebound timing relative to drop deformation is critical for capture success.
• An optimal fiber length exists for maximizing droplet capture efficiency, influenced by fiber mass and length.
• The study provides insights into controlling droplet behavior on flexible substrates.