A three-dimensional direct numerical simulation (DNS) with Level-Set method is applied to the impingement process of a single droplet with diameter of 1.2〜2.2mm on the air-water free surface, and the characteristics of vortices induced below the free surface are investigated by comparing with the experiments. The results show that the present DNS can capture the generation and transportation process of the vortices. The predicted vortex intensity corresponds with the experimental bestfit curve proposed for a larger droplet with diameter of 2.2〜5.6mm. In addition, the comparisons of velocity vectors and scalar concentration fields between the vertical and oblique impingements show that the momentum and mass transfer mechanism are strongly affected by the angle of droplet's impingement.
