The evaporation of a spherical-cap shaped sessile droplet has been extensively studied. However, there is a growing interest in the evaporation of sessile droplets with more complicated geometries, such as an annular droplet. Not only is the evaporation of annular droplets of intrinsic scientific interest in its own right, but it also arises in several practical and industrial contexts, such as the evaporation of a droplet in a well, which occurs in the manufacturing of organic light-emitting diode (OLED) displays, and in the context of a droplet evaporating on a patterned substrate. In the present work, we formulate and analyse a mathematical model for the evaporation of a thin, axisymmetric annular droplet with two circular contact lines. A numerical solution for the concentration of vapour in the atmosphere is discussed, as well as numerical, asymptotic and approximate solutions for the local and total evaporative flux in the diffusion-limited regime. The evolution, and therefore the lifetime, of the droplet in various modes of evaporation, as well as the nature of the deposit left behind on the substrate after the droplet has entirely evaporated, are described both for a spatially-uniform and a diffusion-limited evaporative flux.
| Date of Award | 2 Jun 2023 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | EPSRC (Engineering and Physical Sciences Research Council) |
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| Supervisor | Stephen Wilson (Supervisor) & Alexander Wray (Supervisor) |
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