Lattice Boltzmann simulations for self-propelled jumping of droplets after coalescence on a superhydrophobic surface

3D multiphase lattice Boltzmann simulations for morphological effects on self-propelled jumping of droplets on textured superhydrophobic surfaces

“…From experiments of Wu et al [14], the prefactor was measured in the range from 1.03 to 1.29. The value of the prefactor was 1.05 as determined in our previous 2D simulation [6] and this value determined from this 3D simulation is 1.12. So, a 3D simulation is closer to experimental value and is therefore more accurate.…”

“…5(a) shows that for a fixed value of S (S = 8) the simulated jumping velocity (a solid curve) increases (r b 10 μm) with the droplet radius to a maximum velocity firstly and then decreases with the droplet radius (r N 10 μm). This variation of jumping velocity can be explained based our previous energy analysis as follows [6]. The initial total kinetic energy E k of the coalesced droplet is given by…”

“…The force term F = F int + F g + F s , includes the inter-particle interaction force F int , the gravitational force F g , and the interaction force between solid surface and fluid F s . The expressions of these forces can be referred to previous work [6,8].…”

“…Liu et al [5] used 3D phase field simulations to study coalescence of two identical spherical droplets on a smooth surface with a contact angle of 180°, and they found that downward velocities changed to upward velocities owing to the counter-action of the substrate to the droplet. Most recently, we have carried out a 2D lattice Boltzmann simulation [6] on jumping of saturated liquid droplets from a rough SHS that emerged in a saturated vapor. However, this 2D simulation has the deficiency that the lower contour of the saturated liquid droplet is not free to fall into the gaps between two pillars because the saturated vapor is trapped in the gaps with no place to escape.…”

Investigation of coalescence-induced droplet jumping on superhydrophobic surfaces and liquid condensate adhesion on slit and plain fins

“…Nam et al [4] found that approximately half of the excess surface energy released during the coalescence is efficiently converted to kinetic energy on the superhydrophobic surface before the detachment process. Liu et al [5] used two-dimensional lattice Boltzmann method to simulate the droplet self-propelled jumping on superhydrophobic surfaces. Wang et al [6] established the relation among the coalescence-induced velocity, surface energy, viscous dissipation, and droplet size without consideration of gravity.…”