Virgile Thiévenaz

• PhD
• Chargé de recherche at CNRS

Water usually contains dissolved gases, and because freezing is a purifying process these gases must be expelled for ice to form. Bubbles appear at the freezing front and are then trapped in ice, making pores. These pores come in a range of sizes from microns to millimeters and their shapes are peculiar; never spherical but elongated, and usually f...

This paper is associated with a video winner of a 2021 American Physical Society's Division of Fluid Dynamics (DFD) Milton Van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2021.GFM.V0069.

The formation of gas bubbles in a liquid occurs in various engineering processes, such as during foam generation or agitation and mixing in bubbly flows. A challenge in describing the initial formation of a gas bubble is due to the singular behavior at pinch-off. Past experiments in Newtonian fluids have shown that the minimum neck radius follows a...

The formation of gas bubbles in a liquid occurs in various engineering processes, such as during foam generation or agitation and mixing in bubbly flows. A challenge in describing the initial formation of a gas bubble is due to the singular behavior at pinch-off. Past experiments in Newtonian fluids have shown that the minimum neck radius follows a...

Dip coating consists of withdrawing a substrate from a bath to coat it with a thin liquid layer. This process is well understood for homogeneous fluids, but heterogeneities, such as particles dispersed in liquid, lead to more complex situations. Indeed, particles introduce a new length scale, their size, in addition to the thickness of the coating...

Significance The pinch-off of a liquid drop extruded from a nozzle is a canonical situation that involves a series of self-similar regimes ending in a finite-time singularity. This configuration allows for exploring capillary flows over a large range of scales. In the case of suspension drops, the presence of particles breaks the self-similarity by...

In this study, we investigate the transition between the Newtonian and the viscoelastic regimes during the pinch-off of droplets of dilute polymer solutions and discuss its link to the coil-stretch transition. The detachment of a drop from a nozzle is associated with the formation of a liquid neck that causes the divergence of the local stress in a...

In this study, we investigate the transition between the Newtonian and the viscoelastic regimes during the pinch-off of droplets of dilute polymer solutions and discuss its link to the coil-stretch transition. The detachment of a drop from a nozzle is associated with the formation of a liquid neck that causes the divergence of the local stress in a...

Dip-coating consists in withdrawing a substrate from a bath to coat it with a thin liquid layer. This process is well-understood for homogeneous fluids, but heterogeneities such as particles dispersed in the liquid lead to more complex situations. Indeed, particles introduce a new length scale, their size, in addition to the thickness of the coatin...

When a droplet is generated, the ligament connecting the drop to the nozzle thins down and eventually pinches off. Adding solid particles to the liquid phase leads to a more complex dynamic, notably by increasing the shear viscosity. Moreover, it introduces an additional length scale to the system, the diameter of the particles, which eventually be...

The formation of drops of a complex fluid, for instance including dissolved polymers and/or solid particles, has practical implications in several industrial and biophysical processes. In this Letter, we experimentally investigate the generation of drops of a viscoelastic suspension, made of non-Brownian spherical particles dispersed in a dilute po...

When a droplet is generated, the ligament connecting the drop to the nozzle thins down and eventually pinches off. Adding solid particles to the liquid phase leads to a more complex dynamic, notably by increasing the shear viscosity. Moreover, it introduces an additional length scale to the system, the diameter of the particles, which eventually be...

The formation of drops of a complex fluid, for instance including dissolved polymers and/or solid particles, has practical implications in several industrial and biophysical processes. In this Letter, we experimentally investigate the generation of drops of a viscoelastic suspension, made of non-Brownian spherical particles dispersed in a dilute po...

We experimentally investigate the effect of freezing on the spreading of a water drop. Whenever a water drop impacts a cold surface, whose temperature is lower than 0 °C, a thin layer of ice grows during the spreading. This freezing has a notable effect on the impact: at given Reynolds and Weber numbers, we show that lowering the surface temperatur...

We experimentally investigate the effect of freezing on the spreading of a water drop. Whenever a water drop impacts a cold surface, whose temperature is lower than 0{\deg}C, a thin layer of ice grows during the spreading. This freezing has a notable effect on the impact: at given Reynolds and Weber numbers, we show that lowering the surface temper...

We investigate experimentally the different shapes taken by a water drop freezing during its impact on a cold surface. We show that these shapes are formed by a water film that remains on top of the first formed ice layer. The capillary hydrodynamics of this water film dewetting on its own ice, coupled with its vertical solidification, is thus quan...

This paper is dedicated to the solidification of a water drop impacting a cold solid surface. In the first part, we establish a one-dimensional (1-D) solidification model, derived from the Stefan problem, that aims at predicting the freezing dynamics of a liquid on a cold substrate, taking into account the thermal properties of this substrate. This...

Whenever a water drop impacts a cold surface – whose surface temperature is lower than 0°C – it freezes as it spreads. The solidification slows the drop's spreading down, eases its fragmentation into droplets, leads to the liquid's retraction and gives the frozen drop a certain shape. The nature of the cold surface is crucial in the freezing proces...

We investigate experimentally the solidification of a water drop during its impact on a sub-zero cooled metallic plate. As the drop impacts the substrate, a first thin layer of ice builds-up and pins the water/ice contact line. This ice layer grows as long as the contact line stays stationary. During this particular time $\tau_\text{SCL}$ the conta...