M. Parsa, S. Harmand, K. Sefiane, M. Bigerelle
University of Valenciennes,
Keywords: pattern formation, Marangoni flow, sessile nanofluid drop, binary mixture, evaporation
Summary:After the complete evaporation of a sessile nanofluid drop, different deposition patterns can be formed on a substrate. The study of deposited patterns left after the drying of a drop containing suspensions has a significant role in various industrial and biological applications. A series of experiments were carried out to investigate the effect of a solid surface temperature on the pattern formation of nanoparticles from binary mixture-based nanofluid drops. It was shown that the substrate temperature affect the nanoparticles deposition left after the dry-out of drops. The optical microscopy was used to track the clusters of nanoparticles during the evaporation. The video microscopy showed the different stages of clusters movement, from a chaotic motion to a regular motion. Using infrared thermography technique, the temperature distribution along the free surface of drops was observed. These thermal patterns contribute to a better understanding of the underlying reasons behind the motion of clusters and also the final form of the dried deposits. The authors have shown that the thermocapillary effect plays more important role than the solutal Marangoni flow in the forming process of the dried deposits left by the binary mixture-based nanofluid drops.