Lateral Drop Rebound on a Hydrophobic and Chemically Heterogeneous Surface

Abstract

A drop rebounding from a hydrophobic and chemically heterogeneous surface is investigated using the multiphase lattice Boltzmann method. The behaviors of drop rebounding are dependent on the degrees of the hydrophobicity and heterogeneity of the surface. When the surface is homogeneous, the drop rebounds vertically and the height is getting higher and higher with increases of the surface hydrophobicity. When the surface consists of two different hydrophobic surfaces, the drop rebounds laterally towards the low hydrophobic side. The asymmetrical rebounding is because the unbalanced Young's force exerted on the contact line by the high hydrophobic side is greater than that by the low hydrophobic surface. A set of contours of momentum distribution illustrate the dynamic process of drop spreading, shrinking and rebounding. This work promotes the understanding of the rebound mechanism of a drop impacting the surface and also provides a guiding strategy for precisely controlling the lateral behavior of rebounding drops by hydrophobic degrees and heterogeneous surfaces.

Multiphase curved boundary condition in lattice Boltzmann method

“…13 presents that the drop retracts after hitting the hydrophobic cylinder. This phenomenon is similar to the bouncing of drops on a flat surface [32,52]. Unlike Fig.…”

“…The application of multiphase flows has been the subject of much interest [38][39][40] and several popular multiphase models have been developed. Wen et al [28] proposed a chemical-potential-based multiphase model well applied in measure various types of contact angles [29] and for analyze the lateral rebound of droplets [32]. The chemical potential is the partial differential of the Gibbs free energy to the composition [41].…”

“…A chemical-potential boundary condition was implemented to express the surface wettability, and the contact angle can be not only linearly tuned by the chemical potential of the surface but also accurately measured [29,30]. Recently, Wen et al [31] proposed the chemical potential multiphase model at large density ratios, which not only has a liquid-gas density ratio of more than 10 14 and a very small spurious current, but also has good applications in the lateral rebound of droplets [32].…”

Effects of Surface Tension on the Stability of Surface Nanobubbles

“…Researchers are interested in the extraordinary properties especially for the small gas-side contact angle θ [15][16][17] and the long-term stability of SNB [18][19][20]. On one hand, its gas-side contact angle is much smaller than the angle determined by Young's equation [21], which is the criterion for the equilibrium of the three-phase contact point [22,23]. On the other hand, the long surviving time is far more than the predicted by Epstein and Plesset's theory [24].…”

Virtual Issue: Wettability Gradient Surfaces

“…Such surfaces have been developed over the last three decades . Typically, the wettability gradients are created through topographical or chemical methods. ,− ,, Surfaces involving artificial patterns, bioinspired shapes, or hierarchical textures have been created. − ,, In addition to experimental studies, the behaviors of droplets on wettability gradient surfaces were also explored theoretically, including condensation heat transfer and the fascinating dynamics of drop impact and rebound. − , Potential applications are indicated: in thermal management applications such as heating, ventilation, air-conditioning, and refrigeration systems; in biomedical systems where the lack of an external power supply may be advantageous, including micropump needles and biochips, including diagnostic devices; and in sustainable environmental material interfaces. We hope that you will enjoy reading this sample of a collection of Langmuir publications that present recent and exciting work on this topic.…”