Irina Graur (Aix-Marseille Université, France)

Professor Irina Graur graduated from Lomonosov Moscow State University in Applied Mathematics. She also received her PhD from Moscow State University in 1989 and joined the Keldysh Institute of Applied Mathematics where she set up her activity in the field of rarefied gas dynamics. In 2000, she joined the University of Provence in France and established a group on experimental and numerical study of gas flows at the microscopic scale. She obtained the habilitation to supervise research in 2008 and joined the University of Aix-Marseille as a full professor. Irina Graur has made numerous contributions in the field of rarefied gases for aerospace research. Her current research interests include experimental and numerical characterization of gas properties at the micro and nano scales. She leads the research group “Non-equilibrium phenomena and microfluidics” at IUSTI laboratory. She has participated in the organization of a number of international conferences, workshops and summer schools. She is co-author of more than a hundred journal articles and conference communications.

Title: Gas transport at microscale: experiments and simulations 
Abstract: Gas flow through low-permeability membranes is of great interest, particularly in vacuum technology for applications such as filtration, separation processes, protection, and flow control. These membranes can combine a high mass flow rate with a high degree of rarefaction. This characteristic makes them particularly useful as leak elements, benefiting from the constancy of conductance in the free molecular regime, for example, in the calibration of ionization gauges or mass spectrometers.
The constant volume technique, originally developed for measuring mass flow rates through microchannels, has been adapted to characterize the permeability of low-permeability porous media. This experimental method offers greater accuracy and shorter experiment times compared to other commonly used methods like "pulse-decay" techniques. Additionally, modeling based on gas kinetic theory enables the extraction of useful parameters, such as the “characteristic flow dimension” of a porous medium. Several examples of applying this methodology are presented for various types of porous media and different gases, under both isothermal and non-isothermal conditions.