Computational investigation of deformable droplet evaporation under forced convection

Evaporation of a deformable droplet under convection is investigated and performance of the classical and Abramzon-Sirignano (A-S) models is evaluated. Using the Immersed Boundary/Front-Tracking (IB/FT) method, interface-resolved simulations are performed to examine droplet evaporation dynamics over a wide range of Reynolds (20 <= Re <= 200), Weber (0.65 <= We <= 9), and mass transfer (1 <= BM <= 15) numbers. It is shown that flow in the wake region is greatly influenced by the Stefan flow as higher evaporation rates leads to an earlier flow separation and a larger recirculation zone behind the droplet. Under strong convection, the models fail to capture the evaporation rate especially in the wake region, which leads to significant discrepancies compared to interface-resolved simulations. Droplet deformation greatly influences the flow field around the droplet and generally enhances evaporation but the evaporation rate remains well correlated with the surface area. The A-S model exhibits a reasonably good performance for a nearly spherical droplet but its performance deteriorates significantly and generally underpredicts evaporation rate as droplet deformation increases. The A-S model is overall found to outperform the classical model in the presence of significant convection.