Numerical analysis on dynamics and thermodynamics of a supercooled water droplet considering the dynamic contact angle

Abstract

The dynamics and thermodynamics of a supercooled water droplet impacting on a horizontal cold surface are investigated numerically. A two-dimensional axisymmetric model that considers both the non-equilibrium solidification caused by the supercooling and the dynamic contact angle (DCA) caused by the hysteresis phenomenon is developed to simulate the impacting, spreading, retraction, and freezing processes by combining the coupled volume-of-fluid and level set air–liquid interface capturing method and the Enthalpy-Porosity phase transition method. The common Kistler DCA model is applied to iteratively calculate the real time contact angle of three-phase contact point using the contact line velocity. The DCA model makes the simulation results of the spreading factor more accurate compared with the experimental data than the static contact angle model does. The non-dimensional maximum spreading factors of the room temperature and supercooled water droplet are almost the same in the low Weber number region, but quite different in the high one. The stable spreading factor is independent of the Weber number but increases with the decrease in the contact angle and the increase in the supercooling degree. This study can deepen the understanding of the impacting-freezing mechanism of a supercooled water droplet.

Icephobic materials and strategies: From bio‐inspirations to smart systems

“…For a supercooled water droplet and a low We value, the water droplet shows a similar maximum spreading diameter as the room temperature droplet. However, it shows a smaller maximum spreading diameter at a high We value 103 …”

“…However, it shows a smaller maximum spreading diameter at a high We value. 103 Other factors should also be considered when analyzing the dynamic behavior of water droplets in real situations (such as surface inclination, 104 RH, 95 ambient/substrate temperature, 105,106 etc.). For the inclined SHS, the impacting water droplets asymmetrically spread along the lateral and longitudinal directions, which leads to uneven distributions of the front and rear lamella (Figure 3b).…”

Implementation of IDEAL algorithm based on Delaunay triangular mesh for 2D-compressible flows

“…In the context of the incompressible flow and heat transfer on the structured and unstructured grids, the advantages of IDEAL over other existing algorithms have been comprehensively demonstrated (Sun et al ., 2008a, b). The benefits of IDEAL have been widely confirmed, leading to its wide applications (Desrayaud and Lauriat, 2009; Sun et al ., 2009a, b, 2011a, b; Yu et al , 2019, 2020; Wang et al ., 2021; Deng et al ., 2017; Li et al ., 2019; Sun and Tao, 2023). However, to the best of the authors' knowledge, the presentation and application of compressible IDEAL algorithm in the unstructured grids have not been published in the literature.…”

Freezing of impact water droplets on cold surfaces

“…The previous works [26,168,216,217] have validated the reliability of the above approach. In the experiment, the initial droplet diameter and temperature are D0 = processes and revealing their coupling mechanism.…”

“…To capture the fluid flow and phase change (heat transfer) in the impact and freezing processes of water droplets on cold surfaces, VOF (Volume of fluid) method [213] coupled with Kistler's dynamic contact angle [214] and Solidification/Melting [215] models is adopted in the present study. This approach has been widely used in previous simulations [26,168,216,217].…”