When and how particles are removed by drops.

A dimensionless capillary capture parameter predicts particle removal when a drop collides with a particle, accounting for at least six capillary–friction scenarios.

• Why it matters: Particle adhesion and self-cleaning are studied, but the timing and mechanism of drop-driven removal remain unclear, limiting efficient cleaning for solar panels, windows, and microelectronics.
• What they did: The work combines lattice Boltzmann simulations with confocal microscopy to analyze drop–particle collisions and introduces the capillary capture parameter to forecast removal across varied particle and surface properties.
• The result: Capillary forces have a dual role: the tangential component always promotes removal, while the normal component can hinder it, enabling design guidance beyond hydrophobicity by also reducing particle–surface friction.

AI summary of the abstract · may contain errors · not medical advice · read the paper.