Numerical methodology for simulating particle deposition on superhydrophobic surfaces with randomly distributed rough structures

Abstract

Superhydrophobic coatings with a rough structure and low surface energy have been regarded as new high-efficiency anti-dust solutions. However, current research on the anti-dust mechanism of superhydrophobic materials is still insufficient. Main obstacles are the difficulty in determining the contact state between the dust particle and the rough structure and calculating the contact force accurately. Herein, a new methodology that introduces rough surface discretization and extends the Johnson-Kendall-Roberts (JKR) model to solve the adhesive contact forces of a particle-rough surface was proposed. Further, the lattice Boltzmann method coupled with the JKR-based discrete element method was employed to study the particle deposition characteristics on superhydrophobic surfaces with randomly distributed rough structures. Surfaces with different rough structures were reconstructed using the fast Fourier transformation method. The particle-airflow and rough surface-airflow interactions were calculated using the immersed moving boundary method. The coupling models and computation scheme were validated by comparing the simulation results with those recorded by a high-speed camera. The effects of the particle diameter, airflow inlet velocity, surface energy, and surface structures (characterized by skewness, kurtosis and standard deviation) on particle migration, deposition morphology and deposition rate were compared and analyzed. The results indicate that smaller particles with larger velocities are less likely to be deposited on superhydrophobic surface. Increasing the surface energy of the rough surface can significantly enhance the particle deposition rate owing to the strong particle–surface adhesion force. Further, appropriate surface roughness can reduce particle–surface adhesion and particle energy dissipation during collision, thereby leading to a deposition reduction. However, excessive peaks and deep valleys on the rough surface would hinder the rolling and translation of the particles, thereby resulting in particle accumulation on the surface. Finally, using superhydrophobic surfaces with a skewness of 0 and kurtosis of approximately 5.0, and appropriately reducing the standard deviation of the rough-surface structures can significantly enhance the effect of superhydrophobic surfaces on anti-dust performance.