1. Bullet Education & Experience

  1. Princeton University

Post-Doc, 2009-present

Advisor: Howard Stone

  1. Université Pierre et Marie Curie (UPMC)

Ph. D. in Hydrodynamics, 2009

Supervisor: Frédérique Giorgiutti-Dauphiné

  1. Université Paris-Sud (Orsay)

Magistère (B.S. and Master) in Fundamental Physics, 2006

  1. Bullet Contact information

Camille Duprat

Postdoctoral Research Associate

Mechanical and Aerospace Engineering

Complex Fluids group

Engineering Quad, Room GO2

Email: cduprat [at] princeton [dot] edu

Instabilities of a liquid film coating a vertical fiber

with F. Giorgiutti-Dauphiné, S. Kalliadasis and C. Ruyer-Quil

Wave interactions in a active dispersive-dissipative media: formation of bound states

with D. Tseluiko, S. Saprykin, S. Kalliadasis and F. Giorgiutti-Dauphiné

Elastocapillary imbibition

with J. Aristoff and H. Stone

Fiber coating is of practical importance and occurs in many technical procedures, for example in the manufacturing process of optical fibers. We study experimentally the evolution of a viscous liquid film flowing axisymetrically down a vertical fiber. This system is a simple example of a nonlinear medium with instability, energy dissipation and dispersion, and can thus be used as a prototype for the study of the pattern-formation dynamics of nonlinear systems. The film is always unstable and spontaneously breaks up into a drop-like wavetrain. The competition  between this instability (Rayleigh-Plateau) and the gravity-driven flow leads to two different scenarios. At low flow rates, the system exhibits a self-sustained dynamics with the selection of a regular pattern with a well defined intrinsic frequency, characteristic of an abolsute linear instability. At larger flow rates, irregular wavetrains triggered by inlet noise are observed, corresponding to the characteristic response of a convectively unstable flow. In the convective regime, the flow can be synchronized by imposing periodic perturbations at the inlet. We then observe saturated non-linear traveling waves.

The surface-tension-driven coalescence of flexible structures (elastocapillarity) is relevant to a number of engineering and biological systems, such as the clumping of hair, the failure of micro devices during wet lithography, or more generally whenever a liquid-air interface is moving through a deformable media. We study the dynamics of wetting of flexible boundaries with a combination of experiments, scaling arguments and theory. We consider two model systems, by studying the rise and the spontaneous imbibition of a liquid between flexible sheets clamped at one end, and free to deflect at the other end. The pressure-induced inward deflection of the sheets leads to an unusual propagation of the meniscus, that deviates from the classical diffusive-like behavior.

  1. Bullet Research interests

My research focuses on free surface flows and instabilities. I have previously studied the instability of a liquid flowing on a vertical fiber, and currently I am mostly interested in problems involving the coupling of capillary-driven flows and elastic structures, especially from an experimental point of view. Here are my publications.

Watch a video about the complex fluids group in Princeton.

  1. Bullet Research topics

Camille Duprat

Bound states, i.e. composites of two or more building blocks (particles/bodies) behaving as single objects, appear often in a wide variety of physical settings, from atomic physics and quantum mechanics to biological systems and complex fluids. Here we demonstrate experimentally for the first time novel bound-state-formation phenomena in low-Reynolds-number interfacial hydrodynamics. We consider a viscous film flowing down a vertical fiber. The film is always unstable and spontaneously breaks up into a drop-like wavetrain. In certain regimes the interface is dominated by solitary pulses which continuously interact with each other (i.e. attract or repel) to form bound states. We show that there is a finite number of possible distances between successive pulses. Those distances can be captured by imposing a weak external forcing, thus forming regular patterns of 2-pulses or 3-pulses bound states.

Wetting of flexible fiber arrays

with S. Protière and H. Stone

Fibrous media are ubiquitous functional materials, which often consist of flexible high aspect ratio fibers that can easily deform under capillary forces with many industrial and ecological consequences. We study the influence of a mist of droplets on an elastic array of fibers by considering a finite volume drop on a pair of two flexible fibers, clamped at one end and free to deflect at the other. The elastocapillary deformation of the fibers leads to the spontaneous motion of the drop toward the free ends. The drop either remains compact with minimal spreading or spreads into a long liquid column that coalesces the fibers. We find that there is a critical volume of liquid, hence a critical drop size, above which this coalescence does not occur, and we identify another drop size which maximizes spreading, thus liquid capture. These ideas are applicable to a wide range of fibrous materials.

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