Drying microcharacteristics of volatile and non-volatile droplets on smooth and structured surfaces

¹ Kutateladze Institue of Thermophysics SB RAS, 1 Lavrentyev Ave., Novosibirsk, 630090, Russia.
² Novosibirsk State University, 2 Pirogov Str., Novosibirsk, 630090, Russia.
³ National Polytechnic University of Armenia, Street, Yerevan, 610101, State, Armenia

^* Corresponding author: gatapova@itp.nsc.ru

Abstract

In order to analyze the dynamics of droplet evaporation from solid surfaces and to study the liquid-solid interactions, liquid droplets were deposited on substrates and examined under a microscope. Due to the variation of interfacial tensions at liquid-gas and at liquid-solid the contact line changes depending on the type of solid surface and liquid. In this study, two liquids with different surface tensions (water and ethanol) are employed to examine the effects of evaporation time and to elucidate the underlying mechanisms of solid-liquid interactions. In the case of rapidly evaporating ethanol droplets, the formation of residual droplets and internal currents was observed. In contrast, the evaporation of water droplets resulted in only a change in the shape of the contact line. The paper presents a dependence of the Ohnesorge number on the dimensionless diameter, which characterizes all the considered types of interaction. Additionally, an analysis of the contact angle and contact diameter is presented.