title: Controlling arbitrary humidity without convection.
abstract: In this paper we show a way that allows for the first time to induce arbitrary humidity of desired value for systems without convective flow. To enable this novelty we utilize a semi-closed environment in which evaporation is not completely suppressed. In this case, the evaporation rate is determined both by the outer (open) humidity and by the inner (semi-closed) geometry including the size/shape of the evaporating medium and the size/shape of the semi-closure. We show how such systems can be used to induce desired humidity conditions. We consider water droplet placed on a solid surface and study its evaporation when it is surrounded by other drops, hereon "satellite" drops and covered by a semi-closed hemisphere. The main drop's evaporation rate is proportional to its height, in agreement with theory. Surprisingly, however, the influence of the satellite drops on the main drop's evaporation suppression is not proportional to the sum of heights of the satellite drops. Instead, it shows proportionality close to the satellite drops' total surface area. The resultant humidity conditions in the semi-closed system can be effectively and accurately induced using different satellite drops combinations.
authors.affiliation: Dan F. Smith Dept. of Chemical Engineering, Lamar University, Beaumont, TX 77710, United States.
authors.forename: Priyanka S
authors.initials: PS
authors.lastname: Wasnik
authors.affiliation: Dan F. Smith Dept. of Chemical Engineering, Lamar University, Beaumont, TX 77710, United States.
authors.forename: Hartmann E
authors.initials: HE
authors.lastname: N'guessan
authors.affiliation: Dan F. Smith Dept. of Chemical Engineering, Lamar University, Beaumont, TX 77710, United States. Electronic address: rafael.tadmor@lamar.edu.
authors.forename: Rafael
authors.initials: R
authors.lastname: Tadmor
keywords: Controlled humidity; Evaporation flux; Evaporation rate; Evaporation suppression; Maxwell equation; Relative humidity; Rowan equation; Satellite drop; Surface phenomena