The process of oblique impact of single water drops onto a water film falling down on an inclined wall was observed using a high-speed camera. The angle between the velocity vector of the impacting drop and the normal vector to the inclined wall was set to the values greater than 70°. In our previous experiments for the single water drop impact onto a quiescent water surface, no secondary drop was observed in this large impingement angle range. In the present experiments, however, secondary drops were produced occasionally during the collision process. The production of secondary drops was observed more frequently when the surface of falling liquid film was wavy. The process of the production of secondary drops from the falling water film was investigated using the video images to understand the difference between the drop impacts onto the quiescent film and onto the falling film. It was shown that the secondary drops could be produced when the primary drop collided against the bottom or the top of the wave. In the former case, it was considered that the impingement angle was overestimated in the present work since the effect of surface waviness was not taken into account. This would imply that the occurrence of splashing was predicted more precisely if the local inclination of film surface could be included in evaluating the impingement angle. In the latter case, it was inferred that the liquid flow formed below the film surface by the drop impact penetrated the film surface to produce secondary drops.

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