Wettability-Dependent Damping of Droplet Vibrations on Solid Surfaces

Area of Science:

• Fluid dynamics
• Surface science
• Acoustics

Background:

• Oscillating sessile droplets are vital in inkjet printing, spray cooling, and antifogging technologies.
• Accurate prediction of viscous damping in these systems remains a challenge.
• Current models often neglect bulk dissipation, limiting their accuracy.

Purpose of the Study:

• To develop a more accurate model for viscous damping in oscillating sessile droplets.
• To account for both near-wall and bulk viscous dissipation.
• To provide a framework for understanding droplet damping behavior across different contact angles and viscosities.

Main Methods:

• Derivation of a two-term approximation for decay rates of pinned sessile droplets.
• Comparison of theoretical predictions with experimental and simulation data.
• Analysis of droplet damping for varying contact angles and fluid properties.

Main Results:

• The two-term approximation significantly improves the prediction of viscous damping compared to first-order models.
• The model effectively resolves discrepancies between predicted and observed dampings within practical viscosity ranges.
• Hydrophobic droplets exhibit lower damping than hydrophilic ones, as explained by the model.

Conclusions:

• The developed two-term approximation offers a more robust method for calculating viscous damping in sessile droplets.
• This model enhances understanding of droplet dynamics in applications like inkjet printing and spray cooling.
• The findings suggest potential applications in viscosity measurements using droplet damping characteristics.