초소수성 표면 위 단일 액적의 초기 접촉 조건에 따른 점핑현상연구

Abstract

Droplet jumping process on superhydrophobic surface draw quite an attention lately for extending the duration of dropwise condensation which enhance the heat transfer considerably compared to filmwise condensation. Most researches so far have been focused on analyzing the behavior of merged droplets. During the phase change, higher temperature gradient can be expected near the wall thus interface movement from condensation effect could be much greater compared to the top. This would increase the asymmetry of the surface which will induce drop jumping process. In this paper, we will focus on single droplet jumping from initial asymmetric geometry on superhydrophobic surface. To see the clear distinction of the initial geometric effect, only hydraulic part of the simulation was considered. Interface was numerically tracked by Level Contour Reconstruction Method. Effect from initial contact angle and radius of the droplet was analyzed based on related energy changes during the process. Droplet jumping occurs when the initial contact angle is lower than approximately 120o. We also found that lower initial contact angle has high conversion rate for the kinetic energy thus exhibiting higher jumping velocity. And lowering the radius is also resulting in higher jumping velocity.