Bouncing Dynamics of Drops' Successive Off-Center Impact

Area of Science:

• Fluid Dynamics
• Surface Science
• Materials Science

Background:

• Understanding drop impact dynamics is crucial for applications like anti-icing surfaces.
• Previous research has explored single drop impacts, but successive impacts present unique challenges.

Purpose of the Study:

• To experimentally investigate the bouncing dynamics of a trailing drop impacting a leading drop.
• To analyze the influence of time intervals and Weber numbers on drop coalescence, rebound, and contact time.
• To develop a theoretical model for predicting contact time in successive off-center drop impacts.

Main Methods:

• Experimental investigation of trailing drop impacts on a leading drop with controlled time intervals and Weber numbers.
• Observation of drop behavior, including coalescence, rebound, and impact location (surface vs. liquid film).
• Development and validation of a theoretical model for contact time calculation.

Main Results:

• Impact timing (short vs. large interval) dictates complete or partial coalescence and rebound.
• Weber number determines whether the trailing drop impacts the surface or the leading drop's liquid film.
• Contact time shows a linear dependence on time interval when impacting the surface or receding film, but a sudden increase when impacting the spreading film.

Conclusions:

• A quantitative relationship for contact time in successive off-center impacts has been established.
• The findings provide insights into the inhibition of drop receding by the leading drop's liquid film.
• This research facilitates the design of more effective anti-icing surfaces by understanding drop-surface interactions.