Drop bouncing by micro-grooves

Fink, V.; Cai, Xuan; Stroh, Alexander; Bernard, Ronan; Kriegseis, Jochen; Frohnapfel, Bettina; Marschall, Holger; Wörner, Martin

doi:10.1016/j.ijheatfluidflow.2018.02.014

Cited by 36 publications

(20 citation statements)

References 35 publications

(44 reference statements)

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“…In the advancing phase, where inertial effects dominate, surface roughness is less important in contrast. This behavior is in accordance with the experimental findings on the relaxation phase reported in and was also noted in our previous numerical study .…”

Section: Resultssupporting

confidence: 93%

“…For the liquid phase ( C ≥ 0), the z ‐component of the velocity is initialized with value – U 0 to prescribe the experimental impact velocity of the droplet. Numerical studies in the context of a previous publication proved that initializing the droplet from a certain height above the surface instead from point‐contact has only a small effect. While the advancing phase of spreading and the maximum spreading radius are only slightly affected, the late receding phase may be influenced by the formation of a gas bubble below the droplet, which may form in case the drop is initialized above the surface.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…The numerical value of c is usually chosen on the order of 10 -1 -10. Its magnitude has a slight influence on the spreading process and the maximum spreading radius [39]. For all simulations in the present study, c = 0.5 m s kg -1 is employed.…”

Section: Computational Setupmentioning

confidence: 99%

“…The numerical simulations are performed with a phase‐field method implemented in OpenFOAM which was already validated for various wetting‐related flow problems , including droplet impact and rebound on micro‐grooved structures . The underlying code phaseFieldFoam has also been used to study potential bubble formation during back‐suction of UWS from the delivery line .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Maximum Spreading of Urea Water Solution during Drop Impingement

et al. 2019

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Droplet impingement of urea water solution (UWS) is a common source for liquid film and solid deposits formed in the tailpipe of diesel engines. In order to better understand and predict wetting phenomena on the tailpipe wall, this study focuses on droplet spreading dynamics of urea water solution. Impingement of single droplets is investigated under defined conditions by high‐speed imaging using shadowgraphy technique. The experimental studies are complemented by numerical simulations with a phase‐field method. Computational results are in good agreement with experimental data for the advancing phase of spreading and the maximum and terminal spreading radius, whereas for the receding phase notable differences occur. For the maximum spreading radius, an empirical correlation derived for glycerol‐water‐ethanol mixtures is found to be valid for millimeter‐sized UWS droplets as well. A numerical simulation for a much smaller droplet however indicates that this correlation is not valid for the tiny droplets of UWS sprays in technical applications.

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Section: Resultssupporting

confidence: 93%

Section: Numerical Simulationmentioning

confidence: 99%

Section: Computational Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Maximum Spreading of Urea Water Solution during Drop Impingement

et al. 2019

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“…To overcome this issue, different types of macrostructures have been introduced in the literature to reduce the contact time on a larger contact area. A group of researchers focused on fabrication of macro grooves on the solid surfaces to break the droplet symmetry and change the impact behaviour [11,[18][19][20][21][22]. For example, Song et al [21] designed and fabricated an anisotropic grooved surface, and were able to reduce the contact time by ~45% when the distance between the grooves is comparable to the droplet diameter.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Waves for Active Reduction of Contact Time in Droplet Impact

Biroun

Tao

et al. 2020

Phys. Rev. Applied

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Minimising droplet impact contact time is critical for applications such as self-cleaning, antierosion or anti-icing. Recent studies have used texturing of surfaces to split droplets during impact or inducing asymmetric spreading, but these require specifically designed substrates which cannot be easily reconfigured. A key challenge is to realise an effective reduction in contact time during droplet impingement on a smooth surface without texturing but with an active and programmable control. Our experimental results show that surface acoustic waves (SAWs), generated at a location distant from a point of droplet impact, can be used to minimise contact time by as much as 35% without requiring a textured surface. Besides, the ability to switch on and off the SAWs means that reduction in droplet impact contact time on a surface can be controlled in a programmable manner. Moreover, our results show that by applying acoustic waves, the impact regime of the droplet on the solid surface can be changed from deposition or partial rebound to complete rebound. To study the dynamics of the droplet impact, we developed a numerical model for the multi-phase flow and simulated different droplet impingement scenarios. Numerical results revealed that the acoustic waves could be used to modify and control the internal velocity fields inside the droplet. By breaking the symmetry of the internal recirculation patterns inside the droplet, the kinetic energy recovered from interfacial energy during the retraction process is increased, and the droplet can be fully separated from the surface with a much shorter contact time. Our work opens up opportunities to use SAW devices to minimise the contact time, change the droplet impact regime and program/control the droplet's rebounding on smooth/planar and curved surfaces as well as rough/textured surfaces.

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Bubble Cutting by Cylinder – Elimination of Wettability Effects by a Separating Liquid Film

Wang

Rohlfs

Börnhorst

et al. 2022

Chemie Ingenieur Technik

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Dedicated to Prof. Dr. Thomas Hirth on the occasion of his 60th birthdayExperiments and simulations are presented for the interaction of single bubbles rising in a viscous liquid against a horizontal cylinder (Ø = 4 mm) of varying wettability. The slide-off of small and the cutting of larger bubbles into two daughter bubbles observed in the experiment are reproduced by phase-field simulations. It is shown that in the entire process bubble and cylinder are separated by a liquid film, which eliminates any influence of cylinder wettability. Before the mother bubble splits, a thinning gas thread develops below the cylinder. The rupture of this gas thread can lead to a different number of satellite bubbles depending on the conditions.

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Drop bouncing by micro-grooves

Cited by 36 publications

References 35 publications

Maximum Spreading of Urea Water Solution during Drop Impingement

Maximum Spreading of Urea Water Solution during Drop Impingement

Acoustic Waves for Active Reduction of Contact Time in Droplet Impact

Bubble Cutting by Cylinder – Elimination of Wettability Effects by a Separating Liquid Film

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