Shear-driven off-plane detachment of water drops from superhydrophobic surfaces

Abstract

Shear-driven drop motion is a common phenomenon with critical implications for applications such as aircraft anti-icing, where efficient drop detachment is essential to reduce water retention, limit freezing, and suppress subsequent ice accumulation. While tangential air shear is typically associated with in-plane drop motion, it has not been considered effective for inducing detachment. Here, combining experiments, simulations, and theoretical analysis, we demonstrate that off-plane drop detachment can occur under specific conditions determined by surface wettability, drop radius, and wind speed. Notably, we identify a distinct scaling regime for the critical wind speed required for detachment as a function of drop radius, determined by the balance between lift and restoring force. Our findings advance the fundamental understanding of drop–airflow interactions and offer inspiring design strategies for efficient drop removal.