A synthetic Schlieren method for the measurement of the topography of a liquid interface

Moisy, Frédéric; Rabaud, Marc; Salsac, Kévin

doi:10.1007/s00348-008-0608-z

Cited by 213 publications

(242 citation statements)

References 21 publications

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“…However, the low velocity regime remains to be understood, including the interaction among the vapor layer, the surrounding air, and the drop movement. In addition, the wake created by the moving drop could be characterized, using recently developed tools for measuring liquid surface deformations (20,21). The theoretical description of wave resistance might also be improved, by a more precise description of the deformation of the drop/liquid interface (16), and by taking into account transient effects (22) in this decelerated motion.…”

Section: Resultsmentioning

confidence: 99%

Wave drag on floating bodies

Merrer

Clanet

Quéré

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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We measure the deceleration of liquid nitrogen drops floating at the surface of a liquid bath. On water, the friction force is found to be about 10 to 100 times larger than on a solid substrate, which is shown to arise from wave resistance. We investigate the influence of the bath viscosity and show that the dissipation decreases as the viscosity is increased, owing to wave damping. The measured resistance is well predicted by a model imposing a vertical force (i.e., the drop weight) on a finite area, as long as the wake can be considered stationary.capillary waves | Leidenfrost effect T he drag on floating bodies has three main contributions (1): skin friction, inertial drag associated with vortex emission, and wave drag. In experiments, extracting each contribution from a global drag measurement is often difficult (2, 3). In the special case of hovercrafts, wave drag plays the major role and its magnitude has been determined by ref. 4. For a large vessel, surface waves are dominated by gravity and the author shows that the drag scales as p 2 ffiffiffi S p ∕ρg (S is the area of the cushion and p is the pressure under the hovercraft), and it reaches a maximum for a Froude number V ∕ ffiffiffiffiffiffiffiffiffiffi ffi gS 1∕2 p close to unity (V is the hovercraft speed). Here, we study capillary hovercrafts made of liquid nitrogen drops floating in a Leidenfrost state on the surface of water.Leidenfrost drops are usually created when a liquid is deposited on a plate hot enough to induce a strong evaporation (e.g., water on a plate at 250°C), leading to the formation of a vapor layer between the drop and the plate (5, 6). This vapor film, of thickness between 10 and 100 μm, insulates the drop, allowing lifetimes as long as 1 min for millimetric drops (7). It also dramatically reduces the friction on the drop in this perfectly nonwetting situation. Here we study Leidenfrost drops sliding on a liquid surface and investigate the role of surface deformation on friction. Experimental SetupWe use millimetric liquid nitrogen drops-in a Leidenfrost state at ambient temperature-arriving with some prescribed velocity onto a bath of water or silicone oil of density ρ, surface tension γ, and kinematic viscosity ν (Fig. 1). Using a fast video camera, we record the drop motion from above. A typical sequence is shown in Fig. 2A for a drop of diameter D ≈ 3 mm. Its radius is then comparable to the capillary length for liquid nitrogen a n ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi γ n ∕ðρ n gÞ p ¼ 1.1 mm (γ n ¼ 8.8 mN∕m and ρ n ¼ 808kg∕m 3 are liquid nitrogen's surface tension and density). From the images, we measure the position x of the drop as a function of time t (Fig. 2B). First, we note that the duration of an experiment is less than 1 s, much smaller than the typical 1-min evaporation time of the drop: The drop volume remains almost constant, contrasting with other recent experiments made with nitrogen drops on liquids (8). Second, the curve is smooth, despite the fact that experimentally some shape oscillati...

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Section: Resultsmentioning

confidence: 99%

Wave drag on floating bodies

Merrer

Clanet

Quéré

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Second, it preconditions the bath for a monochromatic wave field. Eddi et al (2011a) characterized the form of the wave field generated by particle impact on a vibrating bath (γ < γ F ) using a free-surface synthetic Schlieren technique (Moisy et al 2009). Following impact, a transient wave propagates away from the impact sight at a speed of ∼ 6cm/s, and in its wake persists a field of standing Faraday waves, whose longevity depends on the proximity to the Faraday threshold.…”

Section: The Faraday Levitatormentioning

confidence: 99%

Pilot-Wave Hydrodynamics

Bush

2015

Annu. Rev. Fluid Mech.

280

343

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Yves Couder, Emmanuel Fort and coworkers have recently discovered that a millimetric droplet sustained on the surface of a vibrating fluid bath may self-propel through a resonant interaction with its own wave field. We review experimental evidence indicating that the walking droplets exhibit certain features previously thought to be exclusive to the microscopic, quantum realm. We then review theoretical descriptions of this hydrodynamic pilot-wave system that yield insight into the origins of its quantum-like behavior. Quantization arises from the dynamic constraint imposed on the droplet by its pilot-wave field, while multimodal statistics appear to be a feature of chaotic pilot-wave dynamics. We attempt to assess the potential and limitations of this hydrodynamic system as a quantum analog. This fluid system is compared to quantum pilot-wave theories, shown to be markedly different from Bohmian mechanics, more closely related to de Broglie's original conception of quantum dynamics, his double-solution theory, and its relatively recent extensions through workers in stochastic electrodynamics.

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“…Moisy et al (2009), for example, recorded a background pattern through a liquid. The liquid was contained in a tank with a transparent bottom allowing for an optimization of the background pattern distance Z D .…”

Section: Free Surface Bosmentioning

confidence: 99%