Publications associées à Knudsen diffusion

Morphology and Transport Characterization of Catalyst Layers for CO2 Reduction

Gas diffusion electrodes (GDEs) help to reduce transport limitations in devices for electrochemical CO2 reduction. Homogenized modeling of such devices requires input of morphological characteristics and effective transport properties of the porous structu ...

2023

Transport barrier in 5D gyrokinetic flux-driven simulations

Two ways for producing a transport barrier through strong shear of the E x B poloidal flow have been investigated using GYSELA gyrokinetic simulations in a flux-driven regime. The first one uses an external poloidal momentum (i.e. vorticity) source that lo ...

IOP Publishing Ltd2022

Hydraulic stimulation of pre-existing discontinuities in tight rocks

Federico Ciardo

Hydraulic stimulation is an engineering technique whose aim is to enhance the permeability of fractured rock masses at depths ranging from one to five kilometers. It consists in the injection of fluid at sufficiently high pressure in order to shear pre-exi ...

EPFL2020

Loopy Levy flights enhance tracer diffusion in active suspensions

Tomohiko Sano, Andrea Cairoli

A theoretical framework describing the hydrodynamic interactions between a passive particle and an active medium in out-of-equilibrium systems predicts long-range Levy flights for the diffusing particle driven by the density of the active component. Browni ...

2020

Bimolecular charge transfer reactions at and through the liquid-liquid interface

Grégoire Clément Gschwend

Interfaces are ubiquitous in Nature. Among them, soft interfaces are essential constituents of biological tissues. Indeed, many electrochemical reactions and phenomena take place at these interfaces. In this respect, ITIES are an interesting model to study ...

EPFL2019

Scaling oxygen microprofiles at the sediment interface of deep stratified waters

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel, Miki Hondzo

Dissolved oxygen microprofiles at the sediment-water interface of Lake Geneva were measured concurrently with velocities 0.25 to 2m above the sediment. The measurements and scaling analyses indicate dissolved oxygen fluctuations and turbulent fluxes in exc ...

American Geophysical Union2017

Fast diffusion of water nanodroplets on graphene

Gabriel Aeppli, Gabriele Tocci, Ming Ma

Diffusion across surfaces generally involves motion on a vibrating but otherwise stationary substrate. Here, using molecular dynamics, we show that a layered material such as graphene opens up a new mechanism for surface diffusion whereby adsorbates are ca ...

Nature Publishing Group2016

Activated carbon fibers modified by metal oxide as effective structured adsorbents for acetaldehyde

Lioubov Kiwi, Guillaume Bastien Baur

Novel efficient adsorbents for acetaldehyde removal from diluted gas streams (similar to 1300 ppmv) have been developed. The adsorbents combine the properties of activated carbon fibers (ACF) and nanoparticles (NPs) of basic metal oxides (La2O3, CaO, MgO, ...

Elsevier Science Bv2015

Microwave gas breakdown in elliptical waveguides

Michael Mattes, Francisco Edén Sorolla Rosario, Ioannis Koufogiannis

This paper analyzes the microwave gas discharge within elliptical waveguides excited by the fundamental mode. The Rayleigh-Ritz method has been applied to solve the continuity equation. The eigenvalue problem defined by the breakdown condition has been sol ...

American Institute of Physics (AIP)2014

Quasi-elastic neutron scattering in the multi-GPa range and its application to liquid water

Livia Eleonora Bove Kado

We present a method which allows quasi-elastic neutron scattering (QENS) at multi-GPa pressures, i.e., pressure conditions which are an order of magnitude higher than possible with QENS till now. The technique uses an opposed-anvil geometry with a sample c ...

Amer Inst Physics2013

Interface structure and flux laws in a natural double-diffusive layering

Alfred Johny Wüest, Martin Schmid

The diffusive regime of double-diffusive convection generates staircases consisting of thin high-gradient interfaces sandwiched between convectively mixed layers. Simultaneous microstructure measurements of both temperature and conductivity from the stairc ...

Amer Geophysical Union2013

Incremental Model Identification of Fluid-Fluid Reaction Systems – Dynamic Accumulation and Reactions in the Diffusion Layer

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

The identification of kinetic models is an important step for the monitoring, control and optimization of industrial processes. This is particularly the case for highly competitive business sectors such as chemical and pharmaceutical industries, where the ...

2013

Tailoring Bimetallic Alloy Surface Properties by Kinetic Control of Self-Diffusion Processes at the Nanoscale

Alfonso Baldereschi, Michele Rizzi

Achieving control of the nanoscale structure of binary alloys is of paramount importance for the design of novel materials with specific properties, leading to, for example, improved reaction rates and selectivity in catalysis, tailored magnetic behavior i ...

Amer Chemical Soc2012

Simulations of a double-diffusive interface in the diffusive convection regime

Alfred Johny Wüest

Three-dimensional direct numerical simulations are performed that give us an in-depth account of the evolution and structure of the double-diffusive interface. We examine the diffusive convection regime, which, in the oceanographically relevant case, consi ...

Cambridge University Press2012

Stability of a Double-Diffusive Interface in the Diffusive Convection Regime

Alfred Johny Wüest

In this paper, the authors explore the conditions under which a double-diffusive interface may become unstable. Focus is placed on the case of a cold, freshwater layer above a warm, salty layer [i.e., the diffusive convection (DC) regime]. The "diffusive i ...

Amer Meteorological Soc2012

Link between Alginate Reaction Front Propagation and General Reaction Diffusion Theory

Jürgen Brugger, Philippe Renaud, Thomas Michael Braschler, Kristopher Pataky, Ana Valero, Ludovica Colella

We provide a common theoretical framework reuniting specific models for the Ca2+-alginate system and general reaction diffusion theory along with experimental validation on a microfluidic chip. As a starting point, we use a set of nonlinear, partial differ ...

2011

Brownian motion studied with an optical trap

Branimir Lukic

This thesis describes measurements of Brownian motion of a colloidal particle using optical trapping. Two aspects are investigated: (i) influence of inertial effects on Brownian motion, and (ii) effect of the optical trap on Brownian motion. The first part ...

EPFL2008

Limited diffusive fluxes of substrate facilitate coexistence of two competing bacterial strains

Dani Or

Soils are known to support a great bacterial diversity down to the millimeter scale, but the mechanisms by which such a large diversity is sustained are largely unknown. A feature of unsaturated soils is that water usually forms thin, poorly-connected film ...

Blackwell Publishing Ltd, Oxford2008

Effective velocity for transport in heterogeneous compressible flows with mean drift

Assyr Abdulle

Solving transport equations in heterogeneous flows might give rise to scale dependent transport behavior with effective large scale transport parameters differing from those found on smaller scales. For incompressible velocity fields, homogenization method ...

2008

Direct Measurement of Effective Diffusion Coefficients in Nanochannels Using Steady-State Dispersion Effects

Philippe Renaud, Arnaud Bertsch, Nicolas Durand, Mina Todorova

We present a method to measure effective diffusion coefficients of fluorescently labeled molecules inside a nanofluidic system. Molecules with small diffusion coefficients show a larger lateral dispersion than highly diffusive species, which is counterintu ...

American Institute of Physics2007