Contact angles and interface behavior during rapid evaporation of liquid on a heated surface

Photographic observations of the boiling phenomena have played an important role in gaining insight into the boiling mechanism. This paper presents a brief historical review of the available literature on the photographic studies in pool and flow boiling. This is followed by the results of the photographic studies conducted in the authorsʹ laboratory on liquid droplets impinging on a heated surface. Liquid–vapor interface and contact line movements are observed through a high speed camera at high resolution. The effect of surface roughness and surface temperature on dynamic advancing and receding contact angles has been studied. In addition, the effects of rapid evaporation on advancing and receding contact angles, liquid–vapor interface motion, and the dryout front propagation have been investigated.