JEFS - Journées Écoulements & Fluides - Saclay

Session

Présentations

22 juin 2026, 09:30

90. Etude numérique comparative des bulles de Taylor en conduites circulaires et carrées

Baptiste Eysseric (CEA Paris Saclay)

22/06/2026 09:30

Présentation orale / Oral presentation

Les bulles de Taylor sont de grandes poches de vapeur immergées présentes dans des conduites ou des microcanaux. Elles apparaissent lors du régime d’écoulement diphasique à bouchons au sein de nombreux systèmes industriels et médicaux. Il est donc essentiel de comprendre leur comportement pour limiter leurs effets indésirables et optimiser les performances des systèmes. Jusqu’à présent, ces...

74. On the gravity-driven flow of Herschel–Bulkley fluids in a syringe and on the jetting-dripping transition

Remi LECANU (UMR SayFood - INRAE)

22/06/2026 09:50

Présentation orale / Oral presentation

Many food and pharmaceutical products present a yield stress, conditioning their flow. In this study, experiments and simulations quantified the effect of yield stress on gravity-driven flow in a syringe. This flow assesses the consistency and swallowing safety of drinks. The jetting-to-dripping transition at the outlet is discussed and an expression is proposed for a critical Weber number...

95. Simulation numérique directe de l’ébullition nucléée dans un mélange binaire H2O-HNO3 avec TrioCFD

Maxime Quentin de Gromard (CEA Paris-Saclay)

22/06/2026 10:10

Présentation orale / Oral presentation

La compréhension de l’impact de l’ébullition sur la corrosion est un enjeu industriel important pour les procédés de retraitement du combustible nucléaire usé qui utilisent un mélange d’eau et d’acide nitrique, porté à ébullition. Dans cette thèse, nous développons l’approche numérique pour la simulation de l’ébullition de mélanges binaires.

L’objectif est de caractériser les cycles de...

73. Iterative Nonlinear Reconstruction of Free-surface Topography using Telecentric Imaging

Shimin Zhang (Universite Paris-Saclay, CNRS, Laboratoire FAST, 91405 Orsay, France)

22/06/2026 10:30

Présentation orale / Oral presentation

The free-surface Synthetic Schlieren (FS-SS) method, originally proposed by Moisy et al. (2009), is a high-resolution, refraction-based optical technique used to measure the instantaneous elevation of liquid interfaces. Traditional FS-SS typically relies on three approximations — small paraxial angles, small slopes and small amplitudes — to establish a linear relationship between the gradient...

77. Singular drainage of liquid films on saddle topographies

Simeon Djambov (LadHyX)

22/06/2026 11:20

Présentation orale / Oral presentation

We investigate the late-time drainage on a substrate featuring a saddle point in the framework of lubrication theory. Unlike stationary points of strictly negative mean curvature, where the film is known to thin in a self-similar fashion (as the inverse of the square root of time), here, the balanced converging and diverging geometry near the saddle point (of vanishing mean curvature) make the...

78. Coulage de flotteurs capillaires par des vagues

Ewen Le Ster (FAST)

22/06/2026 11:40

Présentation orale / Oral presentation

Les microplastiques et autres polluants à la surface de l'océan, bien que généralement plus denses que l'eau, peuvent flotter grâce aux forces capillaires. Néanmoins, l'effet des vagues ou de la turbulence peut rompre cet équilibre de flottaison et conduire à leur immersion. Nous avons étudié la dynamique de disques de laiton placés dans un canal à houle, et notamment l’amplitude minimale de...

85. Numerical approximation of incompressible multiphase flows with pseudo spectral methods

Loic Cappanera (University of Houston)

22/06/2026 12:00

Présentation orale / Oral presentation

The approximation on incompressible flows with variable density and viscosity has many applications in engineering and geosciences (e.g. liquid metal batteries, aluminum production). First, we describe briefly some motivations, classic numerical methods used to the incompressible Navier-Stokes equations with variable density, and the main challenges we face when using pseudo-spectral methods....

104. High-order adaptive multistep coupling scheme for multiphysics applications

M. Antoine Simon (CMAP)

22/06/2026 12:20

Présentation orale / Oral presentation

In the context of multiphysics simulations, partitioned methods enable the reuse of existing solvers while preserving modularity. However, achieving high-order accuracy in time and providing adaptive time stepping remains a challenge, especially when dealing with strong coupling conditions. We address these issues by developing and analyzing a high-order multistep coupling scheme tailored for...

101. Hydrodynamic Coefficients Of Solid And Perforated Heave Plates At Low KC Numbers: A Two-Dimensional ALE CFD Study

M. Kohei Minoda (Institut Polytechnique de Paris - ENSTA Paris)

22/06/2026 14:00

Présentation orale / Oral presentation

Perforated heave plates are widely used to suppress the heave motion of floating offshore wind turbines, yet existing damping models do not disentangle perforation-induced ("hole") and edge-vortex ("edge") damping contributions, preventing scalable physics-based design formulas. As a first step toward the systematic decomposition of these contributions, a two-dimensional ALE finite-volume CFD...

99. Stability-Based Approaches to Flow–Noise Coupling: From Bluff Bodies to Jets

Robin PRINJA (Institut polytechnique des sciences avancées)

22/06/2026 14:20

Présentation orale / Oral presentation

Reducing noise from aircraft and emerging air mobility systems relies on understanding how turbulent flow structures generate and amplify sound.
I will present two complementary lines of research that explore these mechanisms using experimental data and stability-based modeling. First, I will discuss bluffbody aeroacoustics, focusing on Aeolian tones generated in cylinder wakes. By combining...

72. Model Reduction for Fluid-Structure Interaction Involving Moving Surfaces

M. Eren Alagoz (LMPS)

22/06/2026 14:40

Présentation orale / Oral presentation

Fluid-structure interaction (FSI) is a complex multiphysic coupling to implement:

• The two physics are often considered strongly coupled;
• The formalism of each physics differs (Lagrangian/Eulerian);
• Large deformations are present in the fluid and often in the solid;
• Very fine meshing is required to accurately capture certain phenomena (stress concentration, vortices);
• Complex...

81. Flexible fiber dynamics in porous media

Mathis Coutadeur (LadHyX, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris,91120 Palaiseau, France)

22/06/2026 15:00

Présentation orale / Oral presentation

The transport of flexible fibers through complex environments, such as porous and structured media, occurs in a variety of systems like textile microplastics in soils. Additionally, particle sorting or separation using structured media, such as pillar arrays, is essential to many processes, such as biological analysis or environmental assessment. However, due to their deformability and...

100. Invasion of a porous medium saturated by yield-stress fluid: invasion patterns and flow regimes

Nathan Abitbol (Université Paris-Saclay)

22/06/2026 15:40

Présentation orale / Oral presentation

We investigate flows involving yield-stress fluids in porous media using a pore-network model, a simplified representation of porous media. Dynamic two-phase flows are considered, where a Newtonian fluid is injected into a medium initially saturated with a yield-stress fluid. In this system, yield stress competes with both capillarity and viscous forces, leading to the appearance of multiple...

83. Dynamics and Breakup of Liquid Plugs: The Effect of Viscoelasticity

Charlotte DE BLOIS DE LA CALANDE (CNRS, FAST)

22/06/2026 16:00

Présentation orale / Oral presentation

Mucus is a viscoelastic liquid that coats the walls of the lungs, playing a crucial role in air filtration. In diseases such as cystic fibrosis, COPD, and primary ciliary dyskinesia, excessive mucus production and altered rheological properties lead to the formation of mucus plugs. The effect of mucus viscoelasticity on the rupture of these plugs—typically cleared by coughing—has been little...

97. Activity driven flows of dense bacteria suspensions in porous structures

Juan David Torrenegra Rico (Centralesupelec, EMC2 Lab-Universite Paris Saclay)

22/06/2026 16:20

Présentation orale / Oral presentation

Active fluids are known to sustain fluid flows in time without any external forcing. In porous media, active suspensions such as active filaments or microtubules were shown to enhance flow rate, breaking Darcy’s law and inducing mixing without external forces$^{1–3}$. Here, we propose a computational study of dense bacterial suspension flows in porous media. Bacterial suspensions are a class...

93. Nonlinear flow-induced deformation of a confined elastic fiber: toward bio-inspired particle filters

YVAN DURAND TCHATAT MBIANDJEU (LadHyX, Ecole Polytechnique de Paris)

22/06/2026 16:40

Présentation orale / Oral presentation

Dense fibrous media in contact with viscous flows are ubiquitous in nature and technology, from biological filtration systems to engineered porous filters. Their macroscopic transport properties crucially rely on the deformation of individual flexible fibers, yet the elementary fluid–structure mechanisms governing this coupling remain poorly understood.
Here we investigate experimentally and...

84. Observation du régime développé de la turbulence faible d’ondes d’inertie sur la plateforme Coriolis

Benoît CHALET (FAST, CNRS & Université Paris-Saclay)

23/06/2026 09:30

Présentation orale / Oral presentation

L’influence d’une rotation d’ensemble sur la turbulence constitue un des ingrédients clés de la dynamique des écoulements géo et astrophysiques. Une des conséquences de cette rotation est la propagation d’une classe d’ondes spécifiques, appelées ondes d’inertie, dans le volume du fluide. Au sein de la turbulence en rotation, ces ondes et les structures tourbillonnaires classiques de la...

98. Swimming in spatially varying viscosity

Paul Brancher (LadHyX - Ecole polytechnique)

23/06/2026 09:50

Présentation orale / Oral presentation

Oceans are stratified environments, featuring important and sometimes localised gradients of salinity and temperature, that in turn can profoundly affect their mechanical properties (i.e. density and viscosity). These water bodies host a significant part of the Earth’s biomass in the form of microorganisms that swim, feed, and reproduce in such inhomogeneous environments, meanwhile...

92. Développement d’une méthode de PTV 3D3C utilisant une seule caméra & application aux mesures dans un jet d’air pulsé

Tony Kayvantash (IFP Energies Nouvelles)

23/06/2026 10:10

Présentation orale / Oral presentation

Les méthodes de PTV 3D3C nécessitent généralement plusieurs caméras à haute vitesse, ce qui est financièrement couteux et génère des quantités importantes de données à traiter. La méthode développée ici n’en nécessite qu’une seule tout en gardant une bonne précision, ce qui facilite les mesures. Elle repose sur une approche par défocalisation, qui consiste à déduire la position des particules...

75. Dynamics of a Fiber in a Dense Granular Flow

Baptiste Darbois Texier (Laboratoire FAST, CNRS, Université Paris-Saclay)

23/06/2026 10:30

Présentation orale / Oral presentation

Fiber reinforcement of granular materials is a cost-effective strategy widely used in applications ranging from coastal erosion protection to eco-construction materials and fiber-reinforced concretes. The efficiency of such reinforcement strongly depends on the mixing process and on the resulting spatial distribution and orientation of fibers within the granular matrix. To better identify the...

86. Flow patterning at near-zero Reynolds number

Dr Alexandre AVARO (École Polytechnique & Institut Pasteur)

23/06/2026 11:20

Présentation orale / Oral presentation

Microfluidic devices have revolutionized flow control at small scales. Programming localized flow patterns remains challenging. Here, we introduce a new approach to generate programmable and localized flow in microfluidic chips: We use a deformable chip, whose flexible ceiling of the microfluidic channel deforms downward. We leverage this system to break the temporal and spatial symmetries of...

94. Paragliding launch dynamics

Elizabeth Gregorio (LadHyX)

23/06/2026 11:40

Présentation orale / Oral presentation

Paragliding is a new aeronautical sport popularized in the 1980s where pilots fly using fabric wings with a non-rigid structure. Unlike parachutes, paragliders must be inflated and launched before flight. Although many accidents occur at take-off we know little about the physics behind paraglider launch. We present experimental results collected using a custom test bench that simulates the...

89. Physics of Paragliding: Field Measurements and Trajectory Reconstruction of Spiral Descents

Esteban Valdecasa (LadHyX)

23/06/2026 12:00

Présentation orale / Oral presentation

Paragliding is a relatively young adventure sport, popularized in the early 1980s, that involves flying lightweight, free-flying, foot-launched glider aircraft without a rigid primary structure. This design inherently leads to instability, particularly during unsteady phases of flight such as the spiral descent. A spiral descent is characterized by the helical trajectory of both the pilot and...

102. POD as the linear limit of autoencoders: a path to interpretable nonlinear reduced order models

Rémi BOUSQUET (LISN)

23/06/2026 12:20

Présentation orale / Oral presentation

Proper orthogonal decomposition (POD) can be viewed as the linear limit of autoencoders. This connection is exploited to construct interpretable nonlinear reduced order models. By introducing learnable polynomial activation functions, the autoencoder can be initialized as an exact POD decomposition, allowing for an optimal linear reconstruction error even before training begins. Initializing...

87. Numerical Study of a Pintle Injector for an H2/Air Rotating Detonation Combustor

Mathieu CONSTANT (Ensma)

23/06/2026 14:00

Présentation orale / Oral presentation

Rotating Detonation Combustors (RDC) possess a theoretical capacity to increase the engine thermodynamic efficiency compared to the deflagration combustion. Achieving real pressure gain with an experimental RDC remains unattainable because of loss factors depending on the chamber and injector designs, suggesting the need to characterize and further optimize their performance. Large Eddy...

91. Improving the predictivity of large-eddy simulations using machine learning guided by high fidelity simulations

Marwane Trifa (CEA Paris Saclay (DES/ISAS/DM2S/STMF/LDEL) & CNRS (LISN/DATAFLOAT))

23/06/2026 14:20

Présentation orale / Oral presentation

Turbulence is encountered in most industrial flows, yet simulating turbulent flows remains computationally challenging due to the wide range of spatial and temporal scales involved. This breadth of scales induces very high computational costs for Direct Numerical Simulations (DNS), driving the development of more affordable approaches such as Large-Eddy Simulations (LES). However, classical...

79. A Reduced Order Model for predicting the dynamics of the Rayleigh-Taylor Instability

Teo Granger (CEA)

23/06/2026 14:40

Présentation orale / Oral presentation

We study the dynamics of key quantities relevant to RANS modeling of the planar Rayleigh–Taylor instability, averaged along homogeneous directions (1D profiles). Our work relies on a database of 484 DNS of resolution 1048 x 2048 × 2048 points, spanning a wide range of initial conditions.
This dataset serves to build a generalized and interpretable Reduced Order Model (ROM) using Proper...

80. Physics-Informed Neural Network Augmentation of Turbulence Models for the Rayleigh–Taylor Transition

Paul Creusy (CEA, DAM, DIF, F-91297 Arpajon, France)

23/06/2026 15:00

Présentation orale / Oral presentation

Reynolds-averaged Navier–Stokes (RANS) turbulence models are known to perform poorly in predicting the dynamics of Rayleigh–Taylor mixing when turbulence is not fully developed, particularly during the transition from an initially perturbed interface. We investigate the use of data-driven strategies to enhance a simple k–epsilon–S model for this transitional regime. The turbulence model is...

103. Upper versus lower edge state in subcritical shear flows

Yohann Duguet (LISN-CNRS)

23/06/2026 16:00

Présentation orale / Oral presentation

Subcritical shear flows are characterised by the competition between two different attractors, namely the laminar and the turbulent regimes. The concept of “lower” edge manifold refers to the basin boundary in state space, separating initial conditions which
relaminarise from those which become turbulent. It has become central in the study of transition to turbulence. Recent studies have...

105. Transitioning to the ultimate regime of convection in three-dimensional direct numerical simulations

anne SERGENT (LISN)

23/06/2026 16:20

Présentation orale / Oral presentation

Rayleigh-Bénard cavity flows consist of boundary layers sheared by a turbulent wind, which itself is generated by buoyant convection, creating a turbulent bulk. Recently, it has been shown that accounting for the wind Reynolds number resolves the apparent contradiction between the large number of experimental results in the literature (Brichet et al., 2025). A universal critical Reynolds...

88. Multiple coexisting states of viscous sheet folding

Arasakumaran KUMANAN (Laboratoire FAST (CNRS UMR 7608), Universite Paris-Saclay)

23/06/2026 16:40

Présentation orale / Oral presentation

In this work, we investigate the role of inertia in the periodic folding of thin viscous sheets. We employ a mathematical framework inspired by concepts from discrete differential geometry (DDG) to track the motion of the sheet midsurface and capture the shape and dynamics of sheet folding in regimes with non-negligible inertia. We observe that the folding frequency undergoes sudden...

82. Ablation flow sensitivity to ablator density perturbations in ICF

Adrien Gallin

23/06/2026 17:00

Présentation orale / Oral presentation

The hydrodynamic stability of ablation flows is a key issue in laser-driven inertial confinement fusion (ICF) where a sufficiently symmetric implosion of a spherical capsule is expected to achieve thermonuclear burn. More recently, experimental and simulation results have pointed out that ablator internal perturbations could account for degraded capsule performances, emphasizing the need for...