Downward jetting of a dynamic Leidenfrost drop

Lee, Sang-Hyeon; Rump, Maaike; Harth, Kirsten; Kim, Minwoo; Lohse, Detlef; Fezzaa, Kamel; Je, Jung Ho

doi:10.1103/physrevfluids.5.074802

Cited by 19 publications

(20 citation statements)

References 39 publications

(63 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the setup had to be remotely controlled, a laser triggering system was used to sense the falling drop and to trigger the camera and the X-ray beamline shutter. The method has been successfully applied previously to drops impacting on non-heated solid substrates and onto liquid layers [61][62][63] as well as heated substrates 28,30,31 . Heating of the scintillator due to the intense radiation limits the total measurement duration to ≈ 40 ms.…”

Section: Imaging Techniquesmentioning

confidence: 99%

“…In the X-ray data, the drop's bottom is perfectly smooth. As the drop spreads, a vapor rim forms behind the droplet's rim, and capillary waves can evolve on the lamella during retraction 30,31 . The drops rebound by contracting to a slender liquid column from which several smaller satellite drops are usually ejected upwards.…”

Section: Impact Scenariosmentioning

confidence: 99%

“…The same technique can also elucidate the time-dependent contact morphology, e.g., revealing different kinds of fingering structures 24,25 and oscillatory wetting states 25,26 , or solidification in vicinity of a cold plate 27? . Complementary to that, one can determine the height profile of the liquid/vapor contact line projected onto a 2D plane from Ultrafast X-ray phase contrast imaging [28][29][30][31] . From this, the existence of contact is not obvious due to limited spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Drop Impact on Hot Plates: Contact times, Lift-off and the Lamella Rupture

Lee,

Harth,

Rump

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

When a liquid drop impacts on a heated substrate, it can remain deposited, or violently boil in contact, or lift off with or without ever touching the surface. The latter is known as the Leidenfrost effect. The duration and area of the liquid-substrate contact is highly relevant for the heat transfer, as well as other effects such as corrosion. However, most experimental studies rely on side view imaging to determine contact times, and those are often mixed with the time until the drop lifts off from the substrate. Here, we develop and validate a reliable method of contact time determination using high-speed X-ray and Total Internal Reflection measurements. We exemplarily compare contact and lift-off times on flat silicon and sapphire substrates. We show that drops can rebound even without formation of a complete vapor layer, with a wide range of lift-off times. On sapphire, we find a local minimum of lift-off times much shorter than by capillary rebound in the comparatively low-temperature regime of transition boiling / thermal atomization. We elucidate the underlying mechanism related to spontaneous rupture of the lamella and receding of the contact area.

show abstract

Section: Imaging Techniquesmentioning

confidence: 99%

Section: Impact Scenariosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Drop Impact on Hot Plates: Contact times, Lift-off and the Lamella Rupture

Lee,

Harth,

Rump

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…In that geometry, the singular jets emerge from the collapse of the air cavity on the axis of symmetry before rebound [26][27][28][29][30][31]. Similar rebound and jetting dynamics can also be observed * mjthoraval@xjtu.edu.cn for the impact on other surfaces that enable the sliding of the drop during its contraction phase, with the lubrication provided either by the air cushioning [32][33][34][35], the vapor layer produced by the liquid droplet on superheated surfaces [36][37][38][39][40], the sublimation of an ice substrate [41], or the liquid layer on lubricated surfaces [42,43]. In all cases, the "singular" jets, with the largest velocities, are observed near a topological transition of the collapsing interface, either to the rupture of the drop liquid into a toroidal shape [26], or to the entrapment of a bubble at the bottom of the cavity [26,28,29].…”

Section: Introductionmentioning

confidence: 98%

Singular jets in compound drop impact

Mou¹,

Zhang²,

Jian-cun³

et al. 2021

Preprint

View full text Add to dashboard Cite

Compound drop impacting on a solid surface is of considerable importance in industrial applications, such as combustion, food industry, and drug encapsulation. An intriguing phenomenon associated with this process is the occurrence of singular jets that are up to dozens of times faster than the impact velocity. These jets break into micro-droplets, which can produce aerosols and affect the quality of printing technologies. Here, we investigate experimentally and numerically the jetting process after a coaxial water-in-oil compound drop impacts on a glass substrate with different releasing heights and volumetric ratios. After impact, the water core spreads and retracts, giving rise to a vertical jet initially made of oil. For certain values of the impacting velocity, high speed and very thin jets are observed, the so-called singular jets. Depending on the volumetric ratio, one or two velocity peaks can be observed when varying the impact velocity, triggered by the contraction dynamics of a deep and cylindrical cavity. The self-similar time-evolution of the collapse for the first singularity regime follows a 1/2 power law in time, which can be derived from bubble pinch-off. In contrast, the collapse at the second peak follows a 2/3 power law, which can be accounted for by a balance between inertial and capillary forces.

show abstract

“…Our key result is that then, next to the first above-mentioned peak in the drop impact force at drop touch-down, a second peak in the drop impact force occurs, which under certain conditions can be even more pronounced than the first peak. The physical origin of the second peak lies in momentum conservation: when at the final phase of droplet recoil the above-mentioned upward Worthington jet forms, momentum conservation also leads to a downward jet inside the drop [40][41][42][43]. It manifests itself in the second peak in the temporal evolution of the force on the substrate.…”

mentioning

confidence: 99%

Impact forces of water drops falling on superhydrophobic surfaces

Zhang,

Sanjay,

Shi

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

A falling liquid drop, after impact on a rigid substrate, deforms and spreads, owing to the normal reaction force. Subsequently, if the substrate is non-wetting, the drop retracts and then jumps off. As we show here, not only is the impact itself associated with a distinct peak in the temporal evolution of the normal force, but also the jump-off, which was hitherto unknown. We characterize both peaks and elucidate how they relate to the different stages of the drop impact process. The time at which the second peak appears coincides with the formation of a Worthington jet, emerging through flow-focusing, and it is independent of the impact velocity. However, the magnitude of this peak is dictated by the drop's inertia and surface tension. We show that even low-velocity impacts can lead to a surprisingly high peak in the normal force, namely when a more pronounced singular Worthington jet occurs due to the collapse of an air cavity in the drop.

show abstract

Downward jetting of a dynamic Leidenfrost drop

Cited by 19 publications

References 39 publications

Drop Impact on Hot Plates: Contact times, Lift-off and the Lamella Rupture

Drop Impact on Hot Plates: Contact times, Lift-off and the Lamella Rupture

Singular jets in compound drop impact

Impact forces of water drops falling on superhydrophobic surfaces

Contact Info

Product

Resources

About