(559b) Deposits Formed From the Evaporation of Sessile Droplets

The deposition of particles onto a surface from an evaporating sessile droplet was investigated using the Galerkin finite element method to solve the equations governing fluid motion and particle transport. In the computer code that was developed to simulate liquid, vapor and particle phases simultaneously, a convective-diffusive equation along the drop/substrate interface was successfully added into the simulation for more accurate particle deposition profile calculations.  An edge deposition pattern was observed in an experiment with water droplets sitting on a glass substrate suspended with silica particles. The analysis of the interaction potential between silica particles and a glass substrate shows that the deposition rate constant is very small for such case.  A solid phase is considered in this case when the particle concentration reaches the maximum-packing density and the movement of the solid/fluid interface was captured. Simulation results show that under this case, the simulated and experimental edge patterns are in good agreement.