Theoretical Analysis on the Lifetime of Sessile Droplet Evaporation

Abstract

There are two stages for a sessile droplet evaporation on the solid substrate, one is the “constant contact radius” (CR) mode, the other is the “constant contact angle” (CA) mode. In this paper, the theoretical model is built up for sessile droplet evaporation for the two modes, the lifetime of evaporating droplet is obtained under different initial contact radius, initial contact angle and critical contact angle for mode transition. It is found that in the CR mode, the variation of initial contact angle is nonlinear with the time. For both CR and CA modes the lifetime is proportional to R02 (R0 is the initial contact radius of droplet) for two modes. When the critical contact angle for mode transition from CR to CA is increased, the lifetime for CR mode is decreased while the lifetime for CA mode is increased, and the overall lifetime is also increased. This result may be of great significance for sessile droplet evaporation.