https://doi.org/10.1140/epje/i2019-11885-8
Regular Article
Deformation hysteresis of a water nano-droplet in an electric field
1
School of Energy and Power Engineering, Northeast Electric Power University, Jilin, 132012, Jilin, P.R. China
2
The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, 710049, Xi’an, Shaanxi, P.R. China
3
Bioinspired Engineering and Biomechanics Center (BEBC), Xi’an Jiaotong University, 710049, Xi’an, Shaanxi, P.R. China
* e-mail: qzyang@mail.xjtu.edu.cn
Received:
31
March
2019
Accepted:
6
August
2019
Published online:
10
September
2019
Electric field is an effective method to manipulate droplets in micro/nano-scale, and various physical phenomena have been found due to the interaction of electric field and fluid flow. In this study, we developed a molecular dynamic model to investigate the deforming behavior of a nano-droplet in a uniform electric field. The nano-droplet was initially confined between two plates and then wetted on the lower plate (i.e., substrate) until an equilibrium state, after that a uniform electric field in vertical direction was imposed to the system. Due to the electrical force, the droplet started to deform until achieving a new equilibrium state and the dynamic process is recorded. By comparing the equilibrium state under different electric field strength, we found a deformation hysteresis phenomenon, i.e., different deformations were obtained when increasing and decreasing the electric field. To be specific, a large electric field (E = 0.57 V ·nm^-1) is needed to stretch the nano-droplet to touch the upper plate, while a relatively lower field (E = 0.40 V ·nm^-1) is adequate to keep it contacting with the plate. Accompanied by the deformation hysteresis, a distribution hysteresis of the average dipole orientations of water molecules in the nano-droplet is also found. Such a hysteresis phenomenon is caused by the electrohydrodynamic interactions between droplet and plates, and the findings of this study could enhance our understanding of droplet deformation in an electric field.
Key words: Flowing Matter: Interfacial phenomena
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2019