Mechanism of Self-Induced Vibration of a Liquid Drop Based on the Surface Tension Fluctuation

Tokugawa, Naoko; Takaki, Ryuji

doi:10.1143/jpsj.63.1758

Cited by 27 publications

(28 citation statements)

References 9 publications

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“…These techniques are used to measure the frequency of the shape oscillations of the rim as a function of drop size. The results are in good agreement with previous predictions and measurements taken from the outer radius of the drop [8][9][10][11][12]. A breathing mode oscillation in the average radius of the rim is also observed.…”

Section: Introductionsupporting

confidence: 91%

Dynamics of the vapor layer below a Leidenfrost drop

Caswell

2014

Phys. Rev. E

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In the Leidenfrost effect a small drop of fluid is levitated above a sufficiently hot surface, on a persistent vapor layer generated by evaporation from the drop. The vapor layer thermally insulates the drop from the surface leading to extraordinarily long drop lifetimes. The top-view shape of the levitated drops can exhibit persistent star-like vibrations. I extend recent work [Burton et al. PRL 2012] to study the bottom surface of the drop using interference-imaging. In this work I use a high-speed camera and automated image analysis to image, locate and classify the interference fringes. From the interference fringes I reconstruct the shape and height profile of the rim where the drop is closest to the surface. I measure the drop-size dependence of the planar vibrational mode frequencies, which agree well with previous work. I observe a distinct breathing mode in the average radius of the drop, the frequency of which scales differently with drop size than the other modes. This breathing mode can be tightly coupled to a vertical motion of the drop. I further observe a qualitative difference in the structure and dynamics of the vertical profile of the rim between large and small drops.

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Section: Introductionsupporting

confidence: 91%

Dynamics of the vapor layer below a Leidenfrost drop

Caswell

2014

Phys. Rev. E

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“…For example, liquid is drawn by the moving vapor: Balancing the viscous stress in the film η v U/h with the viscous stress in the drop ηV/R, one yields a typical velocity V ∼ U(R/h)(η v /η), that is, approximately 1 cm s −1 for a vapor velocity U = 10 cm s −1 and a film thickness h = 100 μm (as evaluated further below). It was also reported that the temperature in the liquid decreases by a few degrees from the film, where it is at the boiling point, to the top (Bouasse 1924, chapter 7; Tokugawa & Takaki 1994), which generates Marangoni flows. A typical Marangoni velocity V in the liquid is found by balancing the viscous stress ηV/R with the gradient of surface tension γ /R along the drop, which yields V ∼ γ /η, typically 10 cm s −1 in water for γ ≈ 10 −4 mN m −1 , a value corresponding to a temperature difference of a few degrees.…”

Section: Shape Of the Dropsmentioning

confidence: 98%

“…This section discusses some of these special dynamics. The production of vapor also generates special effects, such as self-oscillations (Leidenfrost stars) (Adachi & Takaki 1984, Snezhko et al 2008, Strier et al 2000, Takaki & Adachi 1985, Tokugawa & Takaki 1994, Wachters et al 1966, recently discussed in a short review by Brunet & Snoeijer (2011). In addition, the vapor ejection can be exploited to create self-propulsion (Linke et al 2006), which we describe in Section 3.3.…”

Section: Special Dynamicsmentioning

confidence: 98%

Leidenfrost Dynamics

Quéré

2013

Annu. Rev. Fluid Mech.

456

323

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This review discusses how drops can levitate on a cushion of vapor when brought in contact with a hot solid. This is the so-called Leidenfrost phenomenon, a dynamical and transient effect, as vapor is injected below the liquid and pressed by the drop weight. The absence of solid/liquid contact provides unique mobility for the levitating liquid, contrasting with the usual situations in which contact lines induce adhesion and enhanced friction: hence a frictionless motion, and the possibility of bouncing after impact. All these characteristics can be combined to create devices in which selfpropulsion is obtained, using asymmetric textures on the hot solid surface.

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“…A large number of studies of Leidenfrost drops have focused on the appearance of self-sustained oscillations of the drop [3,5,12,13,14,15,16,17]. These oscillations can sometimes lead to a morphological bifurcation of the drop which takes the shape of a star [3,13,14,16,17].…”

Section: Introductionmentioning

confidence: 99%

Maximum size of drops levitated by an air cushion

2009

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Liquid drops can be kept from touching a plane solid surface by a gas stream entering from underneath, as it is observed for water drops on a heated plate, kept aloft by a stream of water vapor. We investigate the limit of small flow rates, for which the size of the gap between the drop and the substrate becomes very small. Above a critical drop radius no stationary drops can exist, below the critical radius two solutions coexist. However, only the solution with the smaller gap width is stable, the other is unstable. We compare to experimental data and use boundary integral simulations to show that unstable drops develop a gas "chimney" which breaks the drop in its middle.

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Mechanism of Self-Induced Vibration of a Liquid Drop Based on the Surface Tension Fluctuation

Cited by 27 publications

References 9 publications

Dynamics of the vapor layer below a Leidenfrost drop

Dynamics of the vapor layer below a Leidenfrost drop

Leidenfrost Dynamics

Maximum size of drops levitated by an air cushion

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