An impact regime map for water drops impacting on heated surfaces

The impact morphology of millimetric water drops on a polished aluminium surface has been studied experimentally by high-speed imaging, for surface temperatures between 50 and 400 °C, and Weber numbers up to 160. Five impact regimes are defined based on the final outcome of the impact: three independent regimes (secondary atomisation, rebound, and splashing), and two mixed regimes (rebound with secondary atomisation and splashing with secondary atomisation). Impact regimes are displayed on a quantitative two-dimensional map, having the surface temperature and the impact Weber number at ambient conditions as coordinates. Some characteristics of the transition boundaries between impact regimes are discussed.