Evaporation of multicomponent droplets has gained much attention nowadays because of their complex flow fields and various deposition patterns.Here we observe strong flows in evaporating sodium chloride saline droplet...Evaporation of multicomponent droplets has gained much attention nowadays because of their complex flow fields and various deposition patterns.Here we observe strong flows in evaporating sodium chloride saline droplets with suspended alumina oxide nanoparticles.The evolution of flow pattern was studied by tracking the trajectories of particles and the velocity field was investigated with Particle Image Velocimetry analysis.The non-uniform evaporation rate along the droplet surface leads to a concentration gradient which induces the convection flow.During the evaporation process before crystallization happens,evolution of the flow can be divided into two regimes.In Regime I,a centrosymmetric convection recirculation is formed gradually.In RegimeⅡ,the convection recirculation migrates to the droplet edge and evolves into several small vortexes.At the late evaporation stage,crystallization could induce strong convection flows.It is shown that the flow tends to become more chaotic with a lower salt concentration.展开更多
基金The authors acknowledge the support of A*STAR SERC A1783c0006.
文摘Evaporation of multicomponent droplets has gained much attention nowadays because of their complex flow fields and various deposition patterns.Here we observe strong flows in evaporating sodium chloride saline droplets with suspended alumina oxide nanoparticles.The evolution of flow pattern was studied by tracking the trajectories of particles and the velocity field was investigated with Particle Image Velocimetry analysis.The non-uniform evaporation rate along the droplet surface leads to a concentration gradient which induces the convection flow.During the evaporation process before crystallization happens,evolution of the flow can be divided into two regimes.In Regime I,a centrosymmetric convection recirculation is formed gradually.In RegimeⅡ,the convection recirculation migrates to the droplet edge and evolves into several small vortexes.At the late evaporation stage,crystallization could induce strong convection flows.It is shown that the flow tends to become more chaotic with a lower salt concentration.
