Numerical study of droplet impact on a flexible substrate

Area of Science:

• Fluid Dynamics
• Materials Science
• Surface Science

Background:

• Droplet interactions with deformable boundaries are common in nature and industry.
• The flexibility of boundaries significantly alters droplet hydrodynamics.
• Understanding these interactions is crucial for applications involving liquid-solid impacts.

Purpose of the Study:

• To develop a numerical method for simulating droplet impact on flexible substrates.
• To investigate the effects of substrate flexibility on droplet behavior.
• To establish conditions for enhanced droplet rebound and energy conversion.

Main Methods:

• Development of a numerical simulation method for droplet-flexible substrate interactions.
• Parametric study focusing on Weber number and frequency ratios.
• Analysis of energy conversion pathways (kinetic, surface, elastic).
• Proposal of scaling laws using a double spring model.

Main Results:

• A critical Weber number is identified for reduced contact time and increased upward momentum.
• Optimal droplet rebound occurs when the frequency ratio (F_r) approximates the reciprocal of rigid surface contact time (t_ctr).
• Simultaneous conversion of kinetic energy to droplet surface energy and plate elastic energy is observed under specific conditions.
• Scaling laws for maximal plate deflection and droplet spreading diameter were derived.

Conclusions:

• Substrate flexibility can be leveraged to control droplet impact dynamics.
• Specific Weber numbers and frequency ratios are key to efficient energy conversion and rebound.
• Flexibility may promote droplet bouncing even at smaller contact angles, influenced by wettability.