Nanodroplets impact on surfaces decorated with ridges

Liu, Hanyi; Chu, Fuqiang; Zhang, Jun; Wen, Dongsheng

doi:10.1103/physrevfluids.5.074201

Cited by 31 publications

(11 citation statements)

References 52 publications

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“…It was found that liquid possessed a faster retraction along the ridge than that on the flat surface, leading to a 37% reduction in contact time. 21 Following this work, studies focused on contact time reduction by asymmetric dynamics have been carried out, including the inclined surface, 22,23 curved surface, [24][25][26][27][28][29][30] surfaces with macro structures of different geometries, [31][32][33][34][35][36][37][38][39][40] moving surfaces, 41,42 and off-center impact. 43,44 Besides the aforementioned asymmetric approaches, symmetric bouncing by involving the droplet center to retraction with point-like structure to reduce contact time has also been proposed.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of droplet impacting on a cone

Luo

Chu

et al. 2021

Physics of Fluids

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Droplet rebound dynamics on superhydrophobic surfaces has attracted much attention due to its importance in numerous technical applications, such as anti-icing and fluid transportation. It has been demonstrated that changing the macro-structure of the superhydrophobic surface could result in significant change in droplet morphology and hydrodynamics. Here we conduct both experimental and numerical studies of droplet impacting on a cone, and identify three different dynamic phases by changing the impacting conditions, i.e., the Weber number and the cone angle. The spreading and retracting dynamics are studied for each phase. Particularly, it is found that in Phase 3, where the droplet leaves the surface as a ring, the contact time is reduced by 54% compared with that of a flat surface. A theoretical model based on energy analysis is developed to get the rebound point in Phase 3, which agrees well with the simulation result. Besides, the effect of Weber number and cone angle on the contact time is explored.Finally, the phase diagram of the three phases distribution with We and cone angle is given, which can provide guidance to related applications.

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Section: Introductionmentioning

confidence: 99%

Dynamics of droplet impacting on a cone

Luo

Chu

et al. 2021

Physics of Fluids

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“…Nanodroplets have generated a great deal of interest in recent years owing to the rapid development of nanotechnologies such as nanoprinting and nanospray . Recently, complementary to EFD and CFD, molecular dynamics (MD) simulations have been extensively employed to investigate the wetting, spread, rebound, coalescence, etc. of nanodroplets, demonstrating their special abilities in simulating such nanosystems.…”

Section: Introductionmentioning

confidence: 99%

Origin of Rebound Suppression for Dilute Polymer Solution Droplets on Superhydrophobic Substrate

et al. 2021

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Controlling droplet deposition with a minute amount of polymer additives is of profound practical importance in a wild range of applications. Previous work ascribed the relevant mechanisms to extensional viscosity, normal stress, wetting properties, etc., but the mechanism remains controversial. In this paper, we employ molecular dynamics simulations systematically for the first time to investigate the origin of rebound suppression for dilute polymer solution droplets on a flat superhydrophobic substrate. The results demonstrate that polymer−substrate interactions and impact velocities dominate the antirebound phenomenon. For low impact velocities, the dynamic characteristics of droplets are insensitive to polymer additives. However, large impact velocities will enhance the stretch behavior of polymer chains and make the chains closer to the substrate, increasing the probability of polymer molecules contacting the bottom substrate. With the cooperation of strong polymer−substrate interactions, polymer molecules can be absorbed easily by the bottom substrate, resisting the retraction process and leading to the onset of the antirebound behavior.

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“…Theoretically, the moment with the lowest droplet centroid height can be used as the maximum spreading moment, but we found that this could lead to miscalculation in practice, especially on surfaces with high interaction intensity. Refer to the method of Liu et al, 44 the maximum spreading moment t max is defined as the moment when there are most oxygen atoms under the contact layer and we can get the maximum spreading time τ = t max − t start . The specific solution process is given in Section 1 of the Supporting Information.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Head-on Collision of Two Nanodroplets on a Solid Surface: A Molecular Dynamics Simulation Study

et al. 2021

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Most researchers focus on the collision of a single droplet with a solid surface, while it is common for a droplet to collide with a sessile droplet on a solid surface in reality. This study performed the head-on collision of two nanodroplets on a solid surface using the molecular dynamics simulation method. The effects of impact velocity, interaction intensity between solid and liquid atoms, and the solid fraction of the surface on the collision process are studied with independent simulation cases. The maximum spreading factor and the dimensionless maximum spreading time are recorded and calculated to describe the collision process quantitatively. The simulation results indicate that the maximum spreading factor depends more on the solid fraction than the interaction intensity since it does not fundamentally change the wetting state of the droplet at its maximum spreading state. Because of two different effects, the maximum dimensionless spreading time decreases first and then increases with the interaction intensity, and both effects weaken with the increase of impact velocity. As the solid fraction increases, the maximum spreading factor increases significantly at high impact velocity, and the maximum dimensionless spreading time first decreases and then increases because the wetting state of the coalescent droplet at the maximum spreading moment gradually changes from the Wenzel state to the Cassie state. In general, the initial wetting state of the sessile droplet and the wetting state of the coalescent droplet at the maximum spreading moment have important effects on the maximum spreading factor and the maximum spreading time. We establish a theoretical prediction model for the maximum spreading factor on a smooth surface based on energy conservation with quite good accuracy. This research has improved our understanding of the head-on collision process of two nanodroplets on a solid surface.

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Nanodroplets impact on surfaces decorated with ridges

Abstract: This is a repository copy of Nanodroplets impact on surfaces decorated with ridges.

Cited by 31 publications

References 52 publications

Dynamics of droplet impacting on a cone

Dynamics of droplet impacting on a cone

Origin of Rebound Suppression for Dilute Polymer Solution Droplets on Superhydrophobic Substrate

Head-on Collision of Two Nanodroplets on a Solid Surface: A Molecular Dynamics Simulation Study

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