Forced convection enhancing evaporative cooling of a sessile droplet

Sessile droplet evaporation is a promising technique for high-performance thermal management, yet the physical mechanisms governing its enhancement subjected to forced convection remain unclear. This study systematically investigates the enhanced evaporative cooling of a sessile droplet under horizontal channel flow using a high-fidelity, two-dimensional transient multi-physics model. The model, which integrates fluid dynamics, heat transfer, and mass diffusion using the arbitrary Lagrangian–Eulerian (ALE) method, is validated against both published experimental data and established empirical correlations. The results reveal that forced convection imposes an asymmetric shear stress on the droplet interface, which overrides the Marangoni effect and induces a strong, asymmetric internal convection. This shear-dominated internal flow significantly enhances heat transport from the heated substrate to the interface, while the external flow efficiently removes vapor, maintaining a steep concentration gradient. Compared to natural convection, forced convection reduces total evaporation time by approximately 70% and increases the average substrate heat flux by up to 60%. A parametric study further demonstrates that increasing air velocity and decreasing humidity are the most effective strategies for intensifying evaporation, whereas the influence of inlet air temperature is relatively minor. Furthermore, a scaling analysis reveals a general self-similarity, where evaporation dynamics collapse onto master curves, yielding a system-level correlation that extends classical theory for the sessile configuration. This investigation provides insight into the fundamental physics governing evaporation subjected to forced convection, establishing a practical framework for the design and optimization of advanced cooling technologies.