ESPCI web site
Séminaire Café (Interne)
Il s’agit d’un exposé assez court (20 min) et assez informel.
Prière aux conférencier·ère·s de ne jamais dépasser 30 min et de vérifier la compatibilité avec le projecteur avant le séminaire.
Les séminaires ont lieu les jeudis après la réunion du laboratoire qui débute à 13h30 dans la bibliothèque du labo sur le campus Jussieu, Barre Cassan, Bât A, 1er étage.
Pour suggérer un titre et envoyer un abstract, contacter 
et 
.
Coffee seminars are supposed to be short and informal presentations (20 min).
Please never last longer than 30 min and check the compatibility of the projector with your computer before the seminar.
Location : Campus Jussieu, Barre Cassan, Bât A, 1er étage
7 quai Saint Bernard
75005 Paris
To suggest a title or send an abstract, please contact and ..
| 6 mars | Jean-Christophe Lourme - President of ValoTec, Villejuif, France Presentation of ValoTec |
| 13 mars | Alice Marcotte - Institut d’Alembert Tuning the motion of Bretherton’s bubbles : effect of centrifugation and of inclination Air entrapment into liquid-filled channels is encountered in a broad range of applications, from CO2 sequestration in depleted geological oil reservoirs, to embolism in circulatory biological systems. In confined fluid systems, the formation of extended gas bubbles can obstruct channels, eventually compromising circuit performance. Notably, in sealed vertical tubes, elongated bubbles appear stuck if the inner radius is lower than some critical value close to the capillary length. This critical threshold for steady ascent has been shown to be determined by geometrical constraints related to the required matching of the upper cap shape with the lubricating film of vanishing axial curvature developing in the elongated part of the bubble [1,2]. As a matter of fact, in application fields involving narrow liquid channels, long bubbles may be challenging to eliminate. In this context, developing strategies to overcome the motion threshold and release stuck bubbles is desirable. Such strategies require to modify the matching conditions by means of an external force field, in a way that favours bubble ascent. However, it remains unclear how changes in acceleration conditions affect the onset of motion in buoyancy-driven long bubbles. In this talk, we will present our study on transport of long bubbles in sealed tubes filled with a viscous liquid, with an inner radius close to the critical value below which the bubble is stopped in a vertical configuration. Two strategies are explored to tune the bubble motion, which exploit variations of the axial and transversal gravitational accelerations : rotating the tube around its symmetry axis, and inclining it with respect to gravity. By revising and extending the matching conditions and the resulting geometrical constraints of the simple vertical setting, the study predicts the new thresholds based on rotational speed and tilt angle, respectively, providing predictions for the rising velocity of bubbles under modified gravity conditions. Our experimental measurements of motion threshold and rising velocity compare well with the theoretical findings, thus suggesting practical strategies to control and tune bubble motion in confined environments. [1] Bretherton F.P., Journal of Fluid Mechanics 10 (1961). [2] Lamstaes, C. and Eggers, J., Journal of Statistical Physics 167 (2017) [3] Marcotte, A., Ledda, P. G., Buriasco, V., Dené, P., Gallaire, F., and Keiser, L., Journal of Fluid Mechanics, 999, A9 (2024) |
| 20 mars | Lukasz Klotz - Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics (IAAM) Influence of porous material on the flow behind a backward-facing step : experimental study |
| 27 mars | Rencontre du Non-Linéaire |
