ESPCI web site
PMMH’s weekly seminar is held every Friday at 11 am (map)
Alice Pelosse
Stéphane Perrard
Etienne Reyssat
Virgile Thiévenaz
PMMH
BARRE CASSAN
BAT A 1ER ETAGE CASE 18
7 QUAI SAINT BERNARD
75005 PARIS
France
Tel : (33) 1 40 79 45 22
Séminaire PMMH – Cédric Beaume (U. Leeds)
A fluid instability at the origin of salt polygons
Dry salt lakes form spectacular landscapes in arid regions. Strong evaporation and weak precipitation (but also human intervention) can progressively deplete lakes of water, leaving surfaces that appear dry while the water table remains shallow. In such environments, evaporation continues to play an important role, driving dissolved minerals upward and leading to the growth of a salt crust at the surface. These crusts are known to form polygonal patterns with a characteristic wavelength of the order of one meter, bounded by ridges approximately 10cm tall. Remarkably, these patterns show little variability on Earth.
Understanding the formation of these patterns is a fascinating problem in itself, but it is also important for controlling dust emission. In this talk, I will describe the main physical processes driving the fluid dynamics beneath the surface of these lakes. The system is modeled by a three-dimensional porous medium subject to a vertical through-flow induced by evaporation and to buoyancy forces : the presence of a salt crust at the surface yields an unstable stratification and competes with the evaporative drive. I will describe how this instability develops and how it ultimately leads to the emergence of polygonal structures at the surface.
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Seminars (5)
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Séminaire PMMH – Philippe Beltrame (U. Avignon)
Vendredi 27 mars de 11h00 à 12h00 - Salle réunion PMMH 1
Ratchet Effect for Selective Transport of Microparticles in Fluid Suspension
The ratchet effect enables directed transport of particles in noisy systems, even in the absence of a net force (zero bias). When exploited in periodic structures, this phenomenon paves the way for innovative applications in selective microparticle sorting. This seminar will present a theoretical analysis of (…) -
Séminaire PMMH – Jonas Miguet (MSC, Univ. Paris Cité)
Vendredi 3 avril de 11h00 à 12h00 - Salle réunion PMMH 1
Antibubbles : optical interferometry, gas transfers and acoustic signature
An antibubble is a spherical thin film of gas, that encapsulates a droplet, within a liquid medium. The typical size of an antibubble is one centimeter while the thickness of the gas film is of micrometric order. Because of the higher hydrostatic pressure at the bottom, the gas film undergoes a (…) -
Séminaire PMMH – Gautier Verhille (IRPHÉ)
Vendredi 10 avril de 11h00 à 12h00 - Salle réunion PMMH 1
Formation and fragmentation of fiber aggregate in turbulent flows
Fiber aggregates are commonly encountered in environmental and industrial flows (paper industry, fiber recycling, etc.). However, the physical mechanisms leading to their formation are still misunderstood. Hence, there is still no clear answer to simple questions such as : how long will it take for an aggregate to (…) -
Séminaire PMMH – Nicolas Roméo (James Franck Institute, Chicago)
Vendredi 17 avril de 11h00 à 12h00 - Salle réunion PMMH 1
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Séminaire PMMH – Pas de séminaire
Vendredi 24 avril de 11h00 à 12h00 - Salle réunion PMMH 1
The audience is composed of people with rather heterogeneous backgrounds including specialists in solids, fluids, granular flows, statistical physics... so the idea is to keep your talk understandable by people not necessarily working in your field... The seminar time slot runs from 11am to noon so the best is to make the talk last around 45 minutes to leave some time for discussion.
- Séminaires ESPCI-ENS de biophysique
- Séminaires du Département de Physique de l’ENS
- Séminaires du Laboratoire d’Hydrodynamique de l’X
- Séminaire de Mécanique d’Orsay (page web FAST)
- Séminaire de Mécanique d’Orsay (page web LIMSI)
- Séminaire de Mécanique des Fluides de l’Institut Jean le Rond d’Alembert
- Séminaires du laboratoire MSC, Paris VII
- Séminaires Gulliver
Link to cofee seminar (internal, every Thursday)
