Journal of Bionic Engineering ›› 2020, Vol. 17 ›› Issue (4): 802-808.doi: 10.1007/s42235-020-0055-y
Hydrodynamic Pattern in Drying Saline Droplet with Suspended Nanoparticles
Junheng Ren1, Xin Zhong1,2, Lu Shen1, Fei Duan1*
- 1. School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Hydrodynamic Pattern in Drying Saline Droplet with Suspended Nanoparticles
Junheng Ren1, Xin Zhong1,2, Lu Shen1, Fei Duan1*
- 1. School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
摘要： 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 Regime II, 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.