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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Recent seminars (3)
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Séminaire PMMH — Sander Huisman (U. Twente, the Netherlands)
Vendredi 10 juillet de 11h00 à 12h00 - Salle réunion PMMH 1
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Séminaire PMMH — Dmitry Kolomenskiy (Skolkovo Institute of Science and Technology, Russia)
Vendredi 26 juin de 11h00 à 12h00 - Salle réunion PMMH 1
Flight mechanics of the smallest insects
Microinsects with body sizes below 2 millimetres evolved from larger ancestors through natural selection to occupy specialized ecological niches. During miniaturization, many retained their major organs and functions, including the ability to fly. Moreover, microinsects from different orders convergently evolved (…) -
Séminaire PMMH - Carlos Málaga Iguiñiz (UNAM, Mexico)
Vendredi 5 juin de 11h00 à 12h00 - Salle réunion PMMH 1
The Lattice Boltzmann Method
The lattice-Boltzmann method is a relatively new numerical scheme for fluid dynamics simulations. It is a non-conventional method in the sense that it is not built around the equations of fluid motion. Instead, it computes solutions to the Navier-Stokes equations indirectly based on the Boltzmann equation that (…)
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)
