PMMH’s weekly seminar is held every Friday at 11 am (map)
Sylvain Patinet
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  Alex Hansen (NTNU Norvège)
Séminaire d'Alex Hansen (NTNU, Trondheim, Norvège)
The comoving velocity, a new concept in immiscible twophase flow in porous media
Alex Hansen
PoreLab, Department of Physics, NTNU, Trondheim, Norway
Since 1936, relative permeability theory has been the leading description of immiscible twophase flow in porous media at scales much larger than the pore scale. Central to this theory are the two relative permeabilities, one for each fluid, which measures the reduction of mobility each fluid experiences due to the presence of the other fluid. The theory assumes the two relative permeabilities to be functions of the saturation (i.e., relative concentration) alone. When there are saturation gradients present, a third parameter comes into play, the capillary pressure. This is also assumed to depend on the saturation alone.
Such a theory is clearly quite limited in that it makes many strong assumptions. Yet, it is essentially the only one that is used for practical calculations. Can one do better ? That is, come up with a theory that is closer to the physics that is going on and at the same does not drown in complexity ? My answer is yes [17]. The aim of this talk is to describe this new theory. I will focus on a new velocity that pops up, namely the comoving velocity. This velocity has remarkable properties that hints at something deeper which is yet to be uncovered.
References
[1] A. Hansen, S. Sinha, D. Bedeaux, S. Kjelstrup, M. Aa. Gjennestad and M. Vassvik, Relations between seepage velocities in twophase flow in homogeneous porous media, Transp. Porous Med. 125, 565 (2018) ; doi:10.1007/s1124201811396.
[2] S. Roy, S. Sinha, and A. Hansen, Flowarea relations in immiscible twophase flow in porous media, Front. Phys. 8, 4 (2020) ; doi:10.3389/fphy.2020.00004.
[3] S. Roy, H. Pedersen, S. Sinha, and A. Hansen, The comoving velocity in immiscible twophase flow in porous media, Transp. in Porous Media, 143, 69 (2022) ; doi:10.1007/s11242022017837.
[4] A. Hansen, E. G. Flekkøy, S. Sinha, and P. A. Slotte, A statistical mechanics for immiscible and incompressible twophase flow in porous media, Adv. Water Res., 171, 104336 (2023) ; doi:10.1016/j.advwatres.2022.104336.
[5] H. Pedersen and A. Hansen, Parametrizations of immiscible twophase flow in porous media, Front. Phys. 11, 1127345 (2023) ; doi:10.3389/fphy.2023.1127345.
[6] F. Alzubaidi, J. E. McClure, H. Pedersen, A. Hansen, C. F. Berg, P. Mostaghimi and R. T. Armstrong, The impact of wettability on the comoving velocity of twofluid flow in porous media, arXiv:2309.0036.
[7] J. Feder, E. G. Flekkøy, and A. Hansen, Physics of Flow in Porous Media, (Cambridge University Press, 2022).
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Seminars (5)

Séminaire PMMH  François Petrelis (ENS)
Vendredi 31 mai de 11h00 à 12h00  Salle réunion PMMH 1
Earthquake statistical properties : an explanation for the distribution of magnitude and for the existence of aftershocks
Earthquakes in nature follow several statistical properties. In particular, the distribution of energy released by an earthquake (GutenbergRichter's law) and the frequency of aftershocks after a large event (Omori's law) are both powerlaws. By studying several earthquake models, we have shown that the (...) 
Séminaire PMMH  Ko Okumura (Ochanomizu University, Tokyo)
Vendredi 14 juin de 11h00 à 12h00  Salle réunion PMMH 1
A hydrodynamic analog of critical phenomena : an uncountably infinite number of universality classes
When a solid object starts falling into a viscous fluid from airliquid interface, air is entrained into the liquid and eventually detaches from the solid. Such detachment could occur with or without topological change. Recently, it was found that the former case (i.e., breakup, a form of singular transitions) is (...) 
Séminaire PMMH  Ko Okumura (Ochanomizu University, Tokyo)
Vendredi 14 juin de 11h00 à 12h00  Salle réunion PMMH 1
A hydrodynamic analog of critical phenomena : an uncountably infinite number of universality classes
When a solid object starts falling into a viscous fluid from airliquid interface, air is entrained into the liquid and eventually detaches from the solid. Such detachment could occur with or without topological change. Recently, it was found that the former case (i.e., breakup, a form of singular transitions) is (...) 
Séminaire PMMH  Avin Babataheri (Ladhyx)
Vendredi 20 septembre de 11h00 à 12h00  Salle réunion PMMH 1
1D confinement controls cell shape and migration
Pericytes are mural cells of the microvasculature, they wrap around small vessels, support the vessels mechanically and participate in blood flow regulation. Pericytes are distinguished by two main characteristics ; first their distinct morphology, which has been likened to a “bump on a log”, as they present long (...) 
Séminaire PMMH  Avin Babataheri (Ladhyx)
Vendredi 20 septembre de 11h00 à 12h00  Salle réunion PMMH 1
1D confinement controls cell shape and migration
Pericytes are mural cells of the microvasculature, they wrap around small vessels, support the vessels mechanically and participate in blood flow regulation. Pericytes are distinguished by two main characteristics ; first their distinct morphology, which has been likened to a “bump on a log”, as they present long (...)
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 ESPCIENS 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