A Comprehensive Study of Dynamic and Heat Transfer Characteristics of Droplet Impact on Micro-Scale Rectangular Grooved Surface

Micro-scale structure of impact surface has a significant effect on the droplet impact. In this study, a three-dimensional numerical model of the droplet impact on micro-scale rectangular grooved surface was established based on coupled level set and volume of fluid (CLSVOF) method. Furthermore, the evolution of droplet morphology was experimentally studied and the validation of numerical model was carried out. The effects of groove width, contact angle, impact velocity and surface temperature on dynamic and heat transfer characteristics of droplet impact at low Weber numbers were numerically investigated. The anisotropy coefficient is defined to investigate the anisotropy of droplet morphology caused by the micro-scale grooved structure. The numerical results show that vertical spreading diameter is less than parallel spreading diameter, and the anisotropy of droplet morphology tends to reduce gradually with increasing contact angle. Both dynamic and heat transfer characteristics of droplet impact are the coupling effect of contact angle and groove width. The analysis of wettability state is utilized to illuminate the heat transfer characteristics of grooved surface. The maximum heat transfer rate of grooved surface increases with increasing impact velocity and surface temperature, and it decreases with increasing contact angle.