ARTICLE:

• Dynamic of Wetting Line of a Spreading Droplet  download article

S. Sikalo
Faculty of Mechanical Engineering, University of Sarajevo, Vilsonovo setaliste 9, Bosnia/Herzegovina

E. N. Ganic
Faculty of Mechanical Engineering, University of Sarajevo, Vilsonovo setaliste 9, Bosnia/Herzegovina

Cam Tropea
Chair of Fluid Mechanics and Aerodynamics (SLA), TU Darmstadt, Germany, Petersenstr. 30, D-64287 Darmstadt, Germany

ABSTRACT

This paper presents some of the results of an experimental investigation of dynamic contact angle of single spreading droplets. Captured images upon impact of a droplet onto a solid surface were analyzed. On the base of spreading droplet interface upon the impact on a dry surface the evolution of the dynamic contact angle has been quantified. A set of the data obtained in this study is shown. Droplet of an 85% (vol.) glycerin/water solution (D=2.45 mm) was used in the study. Three surfaces, smooth glass (high wettable), wax (low wettable) and rough glass were used, to study the effect of surface wettability (static contact angle) and roughness. Data of the glycerin droplet impact onto 45° inclined surfaces are shown. The results are presented in the form of charts describing the dynamic contact angle of droplets together with the spread factor in terms of time, with the aim to better understanding of contact line motion of an impacting droplet on surfaces. The dynamic contact angle in terms of capillary number is given and compared with the correlation proposed by Jiang at al. (1979).

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259-266 pages

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