The evaporation of an array of droplets on a substrate surface

The evaporation of an array of droplets on a substrate surface is involved in many natural and practical applications varying from macroscale to microscale. As a step to understand the evaporation of an array of droplets, a reduced Point Source Model (PSM) for the evaporation of a pair of sessile droplets sitting on a substrate surface surrounded by quiescent air is developed. The model is developed for a purely diffusive isothermal quasi-steady-state evaporation process. The model is used to determine the initial evaporation rate as a function of the separation distance between the two droplets and the droplet contact angle. A threshold separation distance between the two droplets, beyond which the evaporation rate of the droplets is very similar to the evaporation of a single isolated droplet, was determined. The effect of the evaporation mode was considered to study the variation of the evaporation process parameters with the evaporation time.