Numerical investigation of the freezing property of impinging water droplets on inclined cold superhydrophobic surfaces

We numerically study the freezing process of impinging water droplets on inclined cold superhydrophobic surfaces, concerning the dynamic and heat transfer properties of impinging water droplets. Increasing the surface inclination angle and decreasing the contact angle hysteresis (CAH) is found to promote the rebound of impinging water droplets at a higher cold superhydrophobic temperature (such as −10 °C). The influence of the cold surface temperature on the receding side of impinging water droplets is stronger than that on the front side, and so is the CAH. The frozen region inside impinging water droplets first appears on the receding side, and this becomes more obvious as the surface inclination angle increases. The relatively intensive heat transfer process appears early in the impinging process of water droplets on an inclined cold superhydrophobic surface. Increasing the surface inclination angle could weaken the heat transfer process of impinging water droplets at a higher cold surface temperature (such as −10 °C), but it is not remarkable at a lower cold surface temperature (such as −30 °C). By increasing the supercooling degree, impinging Weber number, and CAH, the freezing process of impinging water droplets is enhanced.