Computational Study of Single Droplet Deposition on Randomly Rough Surfaces: Surface Morphological Effect on Droplet Impact Dynamics

Abstract

Tremendous efforts have been devoted to the modeling of droplet deposition on smooth and patterned surfaces with ordered structures. However, systematic work focusing on randomly rough surfaces, which are the most common bare substrate surfaces, can be hardly identified. A phase field modeling method together with a unique analysis approach has been developed in this work to characterize single droplet deposition on randomly rough surfaces. It is interesting to observe that the droplet shape evolves quite differently on a randomly rough surface, as compared to a patterned surface, even if two surfaces have the same roughness. Parametric studies have been carried out to explore how the morphological metrics of randomly rough surfaces, which include the Wenzel roughness parameter (W r ) and the root-mean-square roughness (R r ), can affect droplet impact dynamics. The quantitative relationships derived from this study can eventually shed light on droplet shape on-aim control during the deposition process, which is of great practical importance in many applications.

Electrothermally Assisted Surface Charge Density Gradient Printing to Drive Droplet Transport

“…The triple-phase contact line was tracked by the phase-field method, and the incompressible liquid–air flow of mass and momentum was represented by the modified Navier–Stokes conservation equations where is the velocity field (m/s), p is the pressure field (Pa), and F is the volume force (N/m 3 ). This accounts for both the interfacial body force, which is used in the phase-field model to include the effects of surface tension and viscosity within the diffusive interface domain, and the gravitational force due to the weight of the falling droplet. where is the gravity vector (m/s 2 ), G is the chemical potential (J/m 3 ), and ϕ is a dimensionless phase-field parameter.…”

“…Governing Equations. The triple-phase contact line was tracked by the phase-field method, 24 and the incompressible liquid−air flow of mass and momentum was represented by the modified Navier−Stokes conservation equations…”

Molecular Dynamics Simulation of Surfactant Flooding Driven Oil-Detachment in Nano-Silica Channels

“…From the experimental perspective, it is still a grand challenge to directly observe the microscopic details of the detachment of oil molecules in the nanochannel . Owing to the rapid development of computer science and technology, computational simulation methods including molecular dynamics (MD), − Monte Carlo (MC), and dissipative particle dynamics (DPD) have been extensively applied to explore the microscopic details of the conformational change and detachment mechanism of oil molecules. − For instance, Yang et al suggest that oil can imbibe into the organic nanopores of rigid rock pores faster than what classic imbibition model prediction and organic nanopores constitute a large portion of pore volume in target tight rocks. Wang et al studied the static properties and pressure-driven flow behavior of liquid n -octane confined in quartz nanopores of shale by MD simulations.…”

Modeling Combined Effects of Temperature and Structure on Competition and Growth of Multispecies Biofilms in Microbioreactors

“…On the other hand, the lattice Boltzmann method (LBM) has the advantage of simulating the multicomponent reactive flow with nonequilibrium interface dynamics in microprocesses . Therefore, the LBM has been applied for geological CO 2 sequestration, , formation and transition of surface condensation, and drop dynamics. , As an ideal framework, the LBM is able to simulate biofilm growth through coupling with iBM , or cellular automata (CA) . Despite progresses, the abovementioned biofilm models are only on monospace biofilm growth in porous media. − ,− Much work remains to be carried out if the LBM is applied for the simulation of multispecies competition and cooperation.…”

“…20 Therefore, the LBM has been applied for geological CO 2 sequestration, 20,21 formation and transition of surface condensation, 22 and drop dynamics. 23,24 As an ideal framework, the LBM is able to simulate biofilm growth through coupling with iBM 25,26 or cellular automata (CA). 27 Despite progresses, the abovementioned biofilm models are only on monospace biofilm growth in porous media.…”