Effects of solution concentration and surface supercooling on the spreading characteristics of an impact binary droplet

We investigate the effect of liquid properties and surface supercooling on the spreading dynamics of an impact binary ethylene-glycol and ethanol droplet. Surface supercooling and solution concentration, affecting the physical properties of a droplet, jointly determine the maximum spreading factor. At a high concentration of ethylene-glycol, the maximum spreading factor decreases with surface supercooling. At a low concentration of ethylene-glycol, the maximum spreading factor decreases and then increases with surface supercooling. The relation between the maximum spreading factor and surface supercooling is resulting from the opposite surface-supercooling-dependencies of the maximum internal spreading factor and the dimensionless fingering length. The maximum spreading factor decreases with the ethylene-glycol concentration due to increased liquid surface tension and viscosity. A new model of the maximum spreading factor, taking into account the effect of surface cooling in viscous dissipation, is proposed based on energy conservation, which optimizes the prediction of spreading of an impact droplet on a surface with different supercooling degrees.