Dynamic and Quasi-static Droplet Penetration through Meshes

Area of Science:

• Fluid Dynamics
• Materials Science
• Surface Science

Background:

• Understanding liquid penetration through porous materials is crucial for various applications, including filtration and protective gear.
• Mesh properties like pore size, surface wettability, and penetration dynamics significantly influence liquid transport.

Purpose of the Study:

• To experimentally investigate the influence of pore size, surface wettability, and penetration mode on liquid penetration characteristics through meshes.
• To determine the key factors governing the threshold speed and mass of liquid penetration under dynamic (droplet impact) and quasi-static (hydrostatic pressure) conditions.

Main Methods:

• Experimental investigation of water penetration through superhydrophobic, hydrophobic, superhydrophilic, and hydrophilic meshes.
• Utilizing droplet impact for dynamic penetration studies and hydrostatic pressure for quasi-static penetration analysis.
• Varying mesh pore radii and pitch values to assess their effects on penetration characteristics.

Main Results:

• Under dynamic droplet impact, surface wettability had a negligible effect on penetration threshold speed and liquid mass.
• The threshold droplet speed for dynamic penetration is primarily governed by the droplet's global and local dynamic pressures.
• For quasi-static penetration, surface wettability and pore pitch did not alter the penetration threshold pressure but affected the cessation pressure due to liquid spreading and capillary effects.

Conclusions:

• Dynamic liquid penetration through meshes is largely independent of surface wettability, driven by impact pressures.
• Quasi-static liquid penetration is influenced by surface wettability and pore pitch, particularly in determining when penetration ceases due to capillary pressure variations.