Analysis of depinning behavior of drop on chemically heterogeneous surface

Bing He, Chunyan Qin, Sihao Zhou, and Binghai Wen
Phys. Rev. Fluids 5, 114003 – Published 13 November 2020

Abstract

The depinning behavior of a drop on an inclined heterogeneous surface comprising hydrophilic-hydrophobic stripes is investigated by the multiphase lattice Boltzmann method driven by the chemical potential. Different initial states of the drop lead to three types of depinning behavior. When the drop is initially in the moderate state, the front and rear contact angles linearly change as the slope angle continues to increase, and depinning almost simultaneously occurs at the front and rear contact lines. Unilateral depinning occurs at the front contact line for the contracted state and at the rear contact line for the elongated state, with sudden instabilities of the contact angle. It is clearly observed that the unilateral depinning process consists of a slow-moving process and a fast-moving process. The dynamic equilibrium reflects the competition between gravity and the capillary force in the whole drop. At the microscopic scale, based on measurement of the real-time contact angle, it is illustrated that the local force balance in the contact line region is maintained by the unbalanced Young's force and the resistance of the substrate in the slow-moving stage, while the unbalanced Young's force provides the driving force for the motion of the contact line in the fast-moving stage.

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  • Received 27 March 2020
  • Accepted 9 October 2020

DOI:https://doi.org/10.1103/PhysRevFluids.5.114003

©2020 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

Bing He1,2, Chunyan Qin1, Sihao Zhou1, and Binghai Wen1,2,*

  • 1College of Computer Science and Information Engineering, Guangxi Normal University, Guilin 541004, China
  • 2Guangxi Key Lab of Multi-source Information Mining & Security, Guangxi Normal University, Guilin 541004, China

  • *oceanwen@gxnu.edu.cn

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Issue

Vol. 5, Iss. 11 — November 2020

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