Lamella evolution of glycerol–water droplets on a rotating surface

Résumé fourni par la source

The study presents an experimental investigation of droplet impact on a rotating smooth stainless-steel surface. High-speed imaging was used to quantify the time-resolved lamella area for water and glycerol–water solutions over rotational speeds from 0 to 10 000 rpm and impact velocities from 1.2 to 1.8 m s−1. The results show that for water droplets, a four-stage lamella evolution is identified at intermediate rotational speeds, consisting of inertia-driven spreading, capillary-driven receding, rotation-induced secondary spreading, and a capillary–centrifugal annular expansion stage. At sufficiently high rotational speeds, capillary-driven receding is fully suppressed, and the lamella expands continuously under rotation-dominated conditions. Increasing viscosity reduces the maximum lamella area and slows capillary-driven recession, while also stabilizing the lamella against rapid thinning. A distinct transition time τtr is identified from the reversal of viscosity ordering in the lamella area: before τtr, more viscous liquids spread less, whereas after τtr, they retain a larger lamella. This reversal is enhanced by rotation but originates from late-time viscous–capillary dynamics rather than from the regime-map transition itself. The normalized transition time remains of order unity relative to the inertial-capillary time, confirming that inertial-capillary relaxation controls the timing of the reversal, while rotation primarily governs the strength of the post-transition reorganization. A regime map and rotational Bond number analysis further distinguish between temporal control of the transition and centrifugal dominance after transition.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.