Containerless Solidification of a Hollow Droplet with Forced Convection

The phenomenon of solidified suspended hollow droplets is often run into industry and nature. In this study, we focus on the containerless solidification process of a hollow droplet undergoing a forcing flow. We found that when the radius ratio (R_io) varied with different growth angles, it changes the trend of the solidification rate of the solidifying front over time. Specifically, with the growth angle of 5° (i.e., Φ_gr = 5°), the suspended hollow droplets finished solidification in almost the same time for R_io in the range of 0.2–0.7. When we increase the growth angle by 5°, i.e., Φ_gr = 10°, the solidification time increases with the increase of R_io. Also following the increase of R_io, this increase in the solidification time is even higher for the growth angle Φ_gr = 15°. The inlet temperature is also considered. Obviously, increasing the inlet temperature increases the solidification time of the hollow droplets. In addition, when the Reynolds number increases, the solidification time of the droplets also tends to increase. However, the increment of this trend is different under different temperatures of the forcing flow.