Research on the contact time of a bouncing microdroplet with lattice Boltzmann method

Tai, Yaolin; Zhao, Yang; Guo, Xinyu; Li, Linan; Wang, Shibin; Xia, Zhenyan

doi:10.1063/5.0046551

Cited by 11 publications

(3 citation statements)

References 43 publications

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“… 39 However, when the viscosity of the liquid is high, viscous forces play a major role in maximum spreading and should be considered. Recently, Tai et al 40 characterized the impact of Newtonian viscous liquids. They reported that increasing the We number increases the maximum spreading radius in liquids with higher viscosities.…”

Section: Resultsmentioning

confidence: 99%

Impact Dynamics of Non-Newtonian Droplets on Superhydrophobic Surfaces

et al. 2023

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Droplet impact behavior on a solid surface is critical for many industrial applications such as spray coating, food production, printing, and agriculture. For all of these applications, a common challenge is to modify and control the impact regime and contact time of the droplets. This challenge becomes more critical for non-Newtonian liquids with complex rheology. In this research, we explored the impact dynamics of non-Newtonian liquids (by adding different concentrations of Xanthan into water) on superhydrophobic surfaces. Our experimental results show that by increasing the Xanthan concentration in water, the shapes of the bouncing droplet are dramatically altered, e.g., its shape at the separation moment is changed from a conventional vertical jetting into a "mushroom"-like one. As a result, the contact time of the non-Newtonian droplet could be reduced by up to ∼50%. We compare the impact scenarios of Xanthan liquids with those of glycerol solutions having a similar apparent viscosity, and results show that the differences in the elongation viscosity induce different impact dynamics of the droplets. Finally, we show that by increasing the Weber number for all of the liquids, the contact time is reduced, and the maximum spreading radius is increased.

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Section: Resultsmentioning

confidence: 99%

Impact Dynamics of Non-Newtonian Droplets on Superhydrophobic Surfaces

et al. 2023

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“…We anticipate that dissipation in the surrounding medium might play a role in the impact of microdrops as increases (Kolinski, Mahadevan & Rubinstein 2014; Tai et al. 2021). Lastly, the influence of the Weber number on the elasticity of the impact process deserves further investigation.…”

Section: Discussionmentioning

confidence: 99%

When does an impacting drop stop bouncing?

2023

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Non-wetting substrates allow impacting liquid drops to spread, recoil and take-off, provided they are not too heavy (Biance et al., J. Fluid Mech., vol. 554, 2006, pp. 47–66) or too viscous (Jha et al., Soft Matt., vol. 16, no. 31, 2020, pp. 7270–7273). In this article, using direct numerical simulations with the volume of fluid method, we investigate how viscous stresses and gravity oppose capillarity to inhibit drop rebound. Close to the bouncing to non-bouncing transition, we evidence that the initial spreading stage can be decoupled from the later retraction and take-off, allowing us to understand the rebound as a process converting the surface energy of the spread liquid into kinetic energy. Drawing an analogy with coalescence-induced jumping, we propose a criterion for the transition from the bouncing to the non-bouncing regime, namely by the condition ${Oh}_{c} + {Bo}_{c} \sim 1$ , where ${Oh}_{c}$ and ${Bo}_{c}$ are the Ohnesorge number and Bond number at the transition, respectively. This criterion is in excellent agreement with the numerical results. We also elucidate the mechanisms of bouncing inhibition in the heavy and viscous drop limiting regimes by calculating the energy budgets and relating them to the drop's shape and internal flow.

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“…For example, in the field of anti-icing, using the rebound characteristic of drops is one of the most promising approaches for its ability to minimize contact time. Contact time is a fundamental parameter representing the rebound characteristic, which plays a key role in enhancing the anti-accumulation performance of superhydrophobic surfaces . Thus, studying the bouncing dynamics and the contact time of drops impacting superhydrophobic surfaces is of direct significance from a fundamental and applied point of view.…”

Section: Introductionmentioning

confidence: 99%

Bouncing Dynamics of Drops’ Successive Off-Center Impact

Gao,

Jia,

Liu

et al. 2024

Langmuir

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Bouncing dynamics of a trailing drop off-center impacting a leading drop with varying time intervals and Weber numbers are investigated experimentally. Whether the trailing drop impacts during the spreading or receding process of the leading drop is determined by the time interval. For a short time interval of 0.15 ≤ Δt* ≤ 0.66, the trailing drop impacts during the spreading of the leading drop, and the drops completely coalesce and rebound; for a large time interval of 0.66 < Δt* ≤ 2.21, the trailing drop impacts during the receding process, and the drops partially coalesce and rebound. Whether the trailing drop directly impacts the surface or the liquid film of the leading drop is determined by the Weber number. The trailing drop impacts the surface directly at moderate Weber numbers of 16.22 ≤ We ≤ 45.42, while it impacts the liquid film at large Weber numbers of 45.42 < We ≤ 64.88. Intriguingly, when the trailing drop impacts the surface directly or the receding liquid film, the contact time increases linearly with the time interval but independent of the Weber number; when the trailing drop impacts the spreading liquid film, the contact time suddenly increases, showing that the force of the liquid film of the leading drop inhibits the receding of the trailing drop. Finally, a theoretical model of the contact time for the drops is established, which is suitable for different impact scenarios of the successive off-center impact. This study provides a quantitative relationship to calculate the contact time of drops successively impacting a superhydrophobic surface, facilitating the design of anti-icing surfaces.

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Research on the contact time of a bouncing microdroplet with lattice Boltzmann method

Cited by 11 publications

References 43 publications

Impact Dynamics of Non-Newtonian Droplets on Superhydrophobic Surfaces

Impact Dynamics of Non-Newtonian Droplets on Superhydrophobic Surfaces

When does an impacting drop stop bouncing?

Bouncing Dynamics of Drops’ Successive Off-Center Impact

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