Surface topography effects on dynamic behavior of water droplet over a micro-structured surface using an improved-VOF based lattice Boltzmann method

A volume of fluid-based lattice Boltzmann method (VOF-LBM) is developed, using the open-source parallel lattice Boltzmann solver library (Palabos) to study the wettability of solid surfaces and include the droplets' dynamic behavior. This improves the accuracy and diminishes limitations on the density and viscosity ratios and the outcoming spurious velocities. An experimental study is performed, and the numerical results are verified through comparison with experimental data. Next, to design novel hydrophobic surfaces with pillar structures, the effect of different pillar patterns and topographies on the contact angle of water droplets and the droplet motion over an inclined surface are investigated. Hydrophobic micro-pillar surfaces are designed to enhance the ease of droplets movement on the slope. The effect of contact angle, wetted area, and surface energy on the sliding behavior of droplets is examined and presented. Results indicate that the new VOF-LBM method can simulate high density and viscosity ratios (1000 and 1.81 x 10(-2) respectively), allowing real-world problems to be analyzed with appropriate accuracy. This reduces the spurious velocities produced at the fluids interface by 19 times compared to the Shan and Chen method. Results demonstrate that the contact angle of the water droplet on the surface with a contact angle of 115 degrees can reach 160 degrees by changing the surface topography. Also, a hydrophobic micro-pillar surface is designed in which the droplet moves nearly 12% faster than the flat surface. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a volume of fluid-based lattice Boltzmann method (VOF-LBM) is developed to investigate the wettability of solid surfaces and dynamic behavior of droplets. Experimental validation is conducted, and the effect of different pillar patterns and topographies on contact angle and droplet motion is studied.