Droplet jump from a particle bed

Area of Science:

• Fluid dynamics
• Microgravity science
• Surface science

Background:

• Droplet behavior is crucial in various industrial and natural processes.
• Understanding droplet interactions with surfaces, especially particle beds, is complex.
• Existing models for droplet dynamics often need refinement for specific conditions.

Purpose of the Study:

• To investigate droplet jump dynamics from particle beds under microgravity.
• To analyze the effect of particle layers on contact line dissipation.
• To validate and extend a spring-mass-damper model for droplet rebound.

Main Methods:

• Experiments conducted using drop tower facilities to simulate microgravity.
• Utilized particle beds made of polyethylene and polystyrene spheres of varying sizes.
• Systematically varied fluid viscosity, Bond number (Bo₀), Weber number (We), and Ohnesorge number (Oh).

Main Results:

• Particle layers were found to significantly affect droplet jumping behavior.
• Contact line dissipation was effectively eliminated by the presence of particle layers.
• A modified spring-mass-damper model accurately predicted droplet jump time and velocity across a wide parameter range.

Conclusions:

• Particle beds offer a method to control droplet dissipation during microgravity transitions.
• The validated model provides a predictive tool for droplet rebound phenomena.
• This research advances the understanding of fluid behavior at interfaces in reduced gravity environments.