Levitation mechanism of impacting nanodroplet on heated wall

Levitation of a droplet after impacting on a high-temperature wall is well known as the Leidenfrost effect. In this study, we conducted a molecular dynamics (MD) simulation to elucidate the mechanism of nanodroplet levitation and to investigate the relation between the levitation mechanism and liquid-solid intermolecular force. We found that the impacting nanodroplet levitated from its edge on the heated wall. Analyses on velocity fields inside the droplet indicated that an upward velocity at the edge of the nanodroplet was caused by an internal flow. The high wall temperature or strong liquid-solid intermolecular force caused an intensive evaporation near the three-phase contact line before levitation occurred, and this intensive evaporation yielded a large internal flow within the nanodroplet.