Open Access

ARTICLE

Droplet Self-Driven Characteristics on Wedge-Shaped Surface with Composite Gradients: A Molecular Dynamics Study

Haowei Hu^1,2,*, Xinnuo Chen¹, Qi Wang¹, Qin Li³, Dong Niu⁴, Mu Du^5,*
1 School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, China
2 Engineering Research Center of Building Energy Efficiency Control and Evaluation, Ministry of Education, Anhui Jianzhu University, Hefei, 230022, China
3 School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei, 230601, China
4 Institute of Refrigeration & Cryogenics Engineering, Dalian Maritime University, Dalian, 116026, China
5 Shenzhen Research Institute of Shandong University, Shandong University, Shenzhen, 518057, China
* Corresponding Author: Haowei Hu. Email: ; Mu Du. Email:

Frontiers in Heat and Mass Transfer https://doi.org/10.32604/fhmt.2024.054218

Received 22 May 2024; Accepted 19 June 2024; Published online 08 July 2024

Abstract

The self-driven behavior of droplets on a functionalized surface, coupled with wetting gradient and wedge patterns, is systematically investigated using molecular dynamics (MD) simulations. The effects of key factors, including wedge angle, wettability, and wetting gradient, on the droplet self-driving effect is revealed from the nanoscale. Results indicate that the maximum velocity of droplets on hydrophobic wedge-shaped surfaces increases with the wedge angle, accompanied by a rapid attenuation of driving force; however, the average velocity decreases with the increased wedge angle. Conversely, droplet movement on hydrophilic wedge-shaped surfaces follows the opposite trend, particularly in terms of average velocity compared to the hydrophobic case. Both wedge-shaped and composite gradient wedge-shaped surfaces are found to induce droplet motion, with droplets exhibiting higher speeds and distances on hydrophobic surfaces compared to hydrophilic surfaces, regardless of surface type. Importantly, the inclusion of wettability gradients significantly influences droplet motion, with hydrophobic composite gradient wedge-shaped surfaces showing considerable improvements in droplet speed and distance compared to their hydrophilic counterparts. By combining suitable wettability gradients with wedge-shaped surfaces, the limitations inherent in the wettability gradient range and wedge-shaped configuration can be mitigated, thereby enhancing droplet speed and distance. The findings presented in this paper offer valuable insights for the design of advanced functional surfaces tailored for manipulating droplets in real-world applications.

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Keywords

Self-driven; wettability gradient; wedge-shaped surface; composite gradient

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