{"id":12783,"date":"2020-11-07T15:25:00","date_gmt":"2020-11-07T14:25:00","guid":{"rendered":"https:\/\/navier-lab.fr\/phd-postdocs\/"},"modified":"2024-09-13T18:05:27","modified_gmt":"2024-09-13T16:05:27","slug":"rmp-phd-postdocs","status":"publish","type":"page","link":"https:\/\/navier-lab.fr\/en\/research\/rheophysics-porous-media\/rmp-phd-postdocs\/","title":{"rendered":"PhD & Postdocs"},"content":{"rendered":"

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Current PhDs & Postdocs<\/h2>\n

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Nicolas Daunais (2024)<\/h4>\n

Philippe Coussot<\/span>
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Hello everyone ! I am Nicolas, and I have started my PhD thesis in February 2024. My research focuses on heat and moisture transfer in buildings constructed using bio-based materials. These materials represent a promising solution to reduce carbon emissions and improve occupant comfort thanks to their ability to absorb bound water in their solid structure. Experts currently assess their performance through macroscopic models that lack a solid physical basis. The aim of my thesis is to develop a numerical model of the hygrothermal behavior of these bio-based materials based on the fine experimental characterization (e.g. through NMR) that is already taking place in the group. These theoretical predictions will be compared to the actual behavior of a real, bio-based building.<\/p>\n

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Kang Hu (2024)<\/h4>\n

Philippe Coussot<\/span>
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I have started working with Philippe Coussot in February 2024 after my PhD and a short postdoc at the University of Tokyo. My PhD focused on the rotational and translational dynamics of water surrounding biomolecules and saccharide molecules using molecular simulation and dielectric spectroscopy. I am interested in interfacial transport phenomena and I am now working on\u00a0 water and heat transfer in hydroscopic, bio-based materials using NMR and MRI techniques. I also enjoy going to the gym, watching basketball and reading during my free time.<\/p>\n

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Van-Truong Nguyen (2023)<\/h4>\n

Philippe Coussot<\/span><\/em>
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Biobased materials have a significant appeal in the construction industry due to their low carbon footprint. Their hygroscopic properties play an important role in their mechanical properties, their durability and indoor environmental quality. These hygrothermal properties are influence by temperature, relatiev humidity, airflow and exposure to liquid water. Standard techniques measure the temperature distribution of a sample along its surface. In this thesis, we develop an orignial technique to access the time-resolved temperature field in the bulk of the material using MRI. An additional challenge will consist in combining this information with humidity measurements over time, to fully characterize the local heat transfers in these materials. We expect this research to significantly improve the predictive capabilities of models describing the hygrothermal properties in biobased materials.<\/p>\n

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Pablo Sanchez-Moreno Royer (2023)<\/h4>\n

Francesco<\/span><\/em> Puosi<\/em>,<\/span> Ana\u00ebl Lema\u00eetre<\/em>
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The goal of my doctoral project is to understand how clay’s thixotropic and rheological properties change over time. This process is poorly known since it is nigh impossible to observe it experimentally. We have then chosen to use molecular dynamics simulations to model these phenomena. Ultimately, this fundamental reseach could lead to greener cement formulation, widespread nuclear waste storage, an improved understanding of soil mechanics and even broader applications in civil engineering.<\/p>\n

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Charlotte Veillon (2023)<\/h4>\n

Xavier Chateau<\/span>, Julie Goyon
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I work on a colloidal suspension containing spherical silica particles and water, which is a model of a cementitious material. The objective of this PhD is to study the effect of adjuvantation (addition of a molecule adsorbing at the particle surface) on the properties of the suspension. I combine rheometry and optical tweezer micromanipulation to assess the properties of these systems at the microscopic and bulk scales.<\/p>\n

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Karen Mourda (2023)<\/h4>\n

Philippe Coussot<\/span>
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I am a PhD student specialized in heat and humidity transfer in bio-based construction materials. I have a background in civil engineering from the Lebanese University, followed by a MSc year in geotechnical engineering and a MSc in the Science of Materials for Sustainable Construction (Master SMCD<\/a>). My reseach focuses on the understanding and characterization of thermal and humidity transfer in cellulose fibers. This work will assuredly yield valuable information on sustainable construction practices and the development of innovative materials in the construction industry.<\/p>\n

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David Richard (2023-2024) : hired as CNRS researcher at PMMH<\/h4>\n

Francesco Puosi<\/span>, Ana\u00ebl Lema\u00eetre
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I am a postdoctoral researcher working together with Francesco Puosi and Ana\u00ebl Lemaitre on the self-assembly and rigidity of colloidal suspensions. The goal of this project is to develop a novel numerical scheme to study the gelation of frictional particles. In particular, we aim at investigating the role of rolling friction on the elasticity and rheology of strongly adhesive suspensions.<\/p>\n

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Imene Ben Djemaa (2023)<\/h4>\n

Florence<\/span> Rouyer, <\/span>J. Goyon-Trohay<\/span>, A. Mikhailovskaya, C. Le C\u0153ur, C. Amiel, F. Cousin (ICMPE)
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My research has been centered on physical chemistry of soft matter, specifically on the science of foams and hydrogels. Interested in the study of formulation\/properties relationships of these materials. My current postdoctoral project focuses on responsive aqueous foams where foam stability can be modulated by external stimuli or changes in environmental conditions. This possibility of reversing the foam from stable to unstable state is interesting for transporting the system to a new functionality.<\/p>\n

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Thi Thu Huyen Bui (2023)<\/h4>\n

Julien L\u00e9opold\u00e8s<\/span>, M. Lebihain (ME & G\u00e9otechnique), G. Cumunel (ME)
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I have been a postdoctoral researcher under the supervisors of Julien L\u00e9opold\u00e8s, Mathias Lebihain, and Gwendal Cumunel since March 2023. My study is to investigate the interaction between process zone and material heterogeneity in the toughening of adhesive interfaces. My work involves experiments on adhesive peeling of a soft elastomer (PDMS) from a micro-patterned interface. The failure mechanisms observed in the experiments are then compared to those predicted by recent models.<\/p>\n

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Yuliang Zou (2022)<\/h4>\n

Philippe Coussot <\/span>
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I have been a postdoctoral researcher working with Philippe\u00a0 since February 2022. My research deals with heat and mass transfer in bio-based construction materials. We aim to explicitly describe the internal physical processes at play in hygrothermal phenomena. We also want to develop suitable physical models to leverage these phenomena. I obtained my PhD thesis in december 2022 from\u00a0 \u00c9cole Centrale Nantes. My thesis evaluated the dynamical effects of porous medium dessication on capillary pressure, with an emphasis on model refinement in terms of unsaturated flow and solid matrix deformation. During my free time, I am passionate about sports, especially football.<\/p>\n

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Luoyi Yan (2022)<\/h4>\n

Philippe Coussot <\/span>
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I started working with Philippe in 2022 and I study the hygrothermal properties of bio-based construction materials. We aim to better understand water transfer in these materials (both in terms of free and bound water). We use NMR to follow diffusion processes in cottonm and we work on developing physical models to harness such processes. We hope that this reseach will promote the use of bio-based materials in the construction sector. Besides labwork, I enjoy reading, playing the flute, attending concerts and travelling !<\/p>\n

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Paul Gauthier (2022)<\/h4>\n

Florence Rouyer<\/span>, Yacine Khidas, Cl\u00e9mence Le C\u0153ur (ICMPE), Alesya Mikhailovskaya (ICMPE)
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Hello! I am Paul, I started my PhD in laboratory Navier in October 2022. The aim of my PhD is to elaborate and study gas marbles<\/em> which are object that can be described as an air bubble surrounded by a liquid film stabilized by particles instead of surfactant. Due to their lightness, their shell properties and their three-phase hierarchical composition, gas marbles have many potential applications, especially in gas encapsulation and vibration dissipation processes. My thesis will focus more specifically on the study of the vibrational properties of gas marbles and their stacking for application in mechanical absorption or acoustics.<\/p>\n

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Ali Salam\u00e9 (2022)<\/h4>\n

Olivier Pitois<\/span>, Vincent Langlois
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I started my PhD with Olivier Pitois and Vincent Langlois on October 2022 as a continuation of my master 2 internship. The context of my PhD is to evaluate the usage of foam in a 3d printing method. Additive Construction method (3d printing) of cementitious materials is one of nowadays most research topics under study especially for its applications in Civil Engineering industries. The method consists of spreading dry aggregates in small layers and bond them locally with cement slurries. Different problems have been faced upon using cement slurry such that penetration problems which affects the bonding between the cement and the aggregates. The idea here is to evaluate a new method based on foam, where we can introduce bubbles into the slurry which will improve the rheological behavior of the material and consequently its transport in porous media. The main parameters to study will be: grain and bubble sizes, air volume fraction in the foam and the rheology of the grout (threshold stress in particular). The latter can be also made with other binders than cement such as geopolymer and calcined clay\u2026 \u00a0Hence, the objective is to tune these parameters in order to control the final microstructure of the produced element and confer significant mechanical strength.<\/p>\n

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Ibrahim Awada (2022)<\/h4>\n

Julien L\u00e9opold\u00e8s<\/span>, Vincent Langlois
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Under load, granular materials behave in a peculiar way, as they suddenly jam or fail and flow. At the grain scale, the mechanisms at play during deformation are poorly understood due to the amorphous nature of such materials. In my thesis, we develop a fine characterization of the local grain dynamics through different techniques : ultrasound diffusion, optical observation and X-ray tomography. We correlate successive ultrasound signals in the multiple diffusion regime by choosing an ultrasound wavelength comparable to the grain size. Overall, we want to brush a precise picture of the evolution of the granular structure under various mechanical loads. We notably expect self-organised structures under cyclic load. To do so, we determine this structure, its evolution and the associated mechanical properties of the granular material as a function of the number of cycles and their amplitude.<\/p>\n

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Nicol\u00f2 Galvani (2021)<\/h4>\n

Olivier Pitois<\/span><\/em>, Sylvie Cohen-Addad (INSP Paris)
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Hello! I started my PhD in 2021 with Olivier Pitois (Navier) and Sylvie Cohen-Addad (INSP), continuing my internship work. My research focuses on the production and aging of foamed emulsions. Foams naturally evolve as pressure differences between bubbles cause a general growth in a process called coarsening. They also undergo gravitational drainage, leading to material inhomogeneities. By studying foams from emulsions with yield stress, we can counteract drainage and isolate coarsening, examining how it varies with yield stress up to the point of stopping it. Construction materials possess yield stress and can be foamed to increase insulating properties: we hope to provide a better understanding of how they age before solidification. In my free time, I am passionate about fiction, board games, and role-playing games, embracing my inner nerd.<\/p>\n

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Ahmad Awdi (2021)<\/h4>\n

Abdoulaye Fall<\/span><\/em>, Jean-No\u00ebl Roux, Camille Chateau (ME)
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Hello! I started my PhD in October 2021 with Abdoulaye Fall, Camille Chateau and Jean-No\u00ebl Roux. I have a diploma in civil engineering, a MSc in hydrosciences from the Lebanese University, followed by a MSc in the Science of Materials for Sustainable Construction (Master SMCD) from \u00c9cole des ponts paristech. The behavior of unsaturated wet granular materials is central to applications ranging from geotechnical engineering to environmental science. My thesis delves into the microstructural dynamics and viscous dissipation of these materials in the pendular regime. Through X-ray microtomography and rheometric measurements, we aim to link the microstructural characteristics to their macroscopic rheological properties under imposed loading conditions.<\/p>\n

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Former PhDs & Postdocs<\/h2>\n

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Yashu Kharbanda (2023 – 2024)<\/h4>\n

Rahima Sidi-Boulenouar
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Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque fermentum neque ac est eleifend congue. Curabitur consequat diam quis tincidunt ultrices. Praesent varius nisi eget purus fringilla, eu tincidunt dolor pulvinar. Vivamus tincidunt nisi ante, aliquet elementum elit pretium ut. In eleifend neque lorem. Pellentesque varius in neque a luctus. Nulla interdum sollicitudin est in viverra. Donec a efficitur est. Vestibulum luctus justo dolor, eu pellentesque velit rhoncus ornare. In gravida id magna suscipit posuere. Aliquam erat volutpat. Nunc ut nisl eros. Duis cursus nulla vel enim venenatis, varius porttitor lorem auctor. Cras pulvinar lobortis nunc, vitae maximus sem cursus nec. Curabitur id fermentum nunc. Duis eget turpis quis enim tincidunt consectetur. Nullam quis ex vestibulum urna molestie tristique. Ut condimentum, justo eget facilisis malesuada, eros diam feugiat purus, non faucibus nibh felis ac elit.<\/p>\n

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Margaux Ceccaldi<\/a> (2020 – 2023) : now at GETELEC<\/h4>\n

Olivier Pitois<\/span><\/em>, Vincent Langlois, Daniel Grande (ICS Strasbourg),\u00a0<\/em>Marielle Gu\u00e9gen-Minerbe (CPDM)<\/em><\/p>\n

Hi! I’m Margaux, I started my PhD in laboratory Navier in october 2020. I work with Olivier Pitois (Navier), Daniel Grande (ICMPE) as co-directors and Vincent Langlois (Navier), Marielle Gu\u00e9guen (CPDM) and Benjamin Carbonnier (ICMPE) as co-supervisors. This project focuses on the development of controlled microstructured material from the foaming of aqueous particles suspension which will be bio-calcified via bacteria activity. Some bacteria produce calcite oxide under the right conditions. We plan to use these bacteria to strengthen the structure of particles in a foam and obtain a more resistant material in the application of insulation or soils (for instance). The challenge is to find the appropriate formulation of the system foam\/particle\/bacteria to keep bacteria both alive and working for the consolidation of the structure.<\/p>\n

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Nabil Retailleau<\/a> (2020 – 2023)<\/h4>\n

Florence Rouyer<\/span><\/em>, Yacine Khidas<\/em><\/p>\n

Liquid films are the subject of numerous studies aimed at addressing various industrial challenges, such as the controlled design of foams for use in the food, mining, or civil engineering industries. Their stability and aging remain relevant questions. There are various methods to stabi\u0002lize a liquid film, including the use of soluble surfactants, referred to as soap films, or solid particles, known as particle-laden films. Here, we focus on soap films suspended in the air, with both inter\u0002faces bridged by non-colloidal solid grains, referred to as granular films. My thesis focused on studying the influence of capillary forces on the rupture behavior and vibrational response of a very dense granular film (grains occupy 87% of the film\u2019s surface). We have designed experimental setups to create granular films and control the liquid pressure between the particles to observe their behavior to pressure variations, investigate their opening after induced rupture, and characterize their vibrational modes. Different opening regimes have been observed, depending on this pressure : for liquid pressures close to atmospheric pressure, the dense granular film bursts like a soap film ; beyond a critical depression, the film\u2019s opening is stopped.<\/p>\n

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Kassem Nejmeh<\/a> (2020 – 2024)<\/h4>\n

Nicolas<\/em> Roussel<\/em><\/span>, Emmanuel Keita (Multi-\u00c9chelles), Ann Bourges (C2RMF)<\/em><\/p>\n

Hello! I am Kassem Nejmeh I am a civil engineer graduated from the Lebanese University followed by International Mater in Advanced Clay Science at University of Poitiers. Currently, I am continuing my PhD studies at University Gustave Eiffel in collaboration with Saint Gobain Company. The aim of this PhD is to improve the resistance of clay mortars to water, by understanding the mechanisms and finding solutions to improve it. Clay materials present in the city of tomorrow through new techniques of bio-based eco-construction with very low energy footprints. Studies of soil stabilization using natural or synthetic additives have also been performed by some researches to evaluate the durability performance of earth as construction materials. These studies showed the possibility to obtain earth architecture with greater durability against water actions. This increase of earth building durability could help to change the inappropriate and prejudiced perception still existing about earth material.<\/p>\n

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Antoine Aubel<\/a> (2020 – 2023) : Now at l’Or\u00e9al<\/h4>\n

Xavier Chateau,<\/span> Julie Goyon, Ana\u00ebl Lema\u00eetre<\/em><\/p>\n

I’m Antoine and I graduated from ENSCI Limoges. My PhD work at Navier Lab with Xavier Chateau and Julie Goyon focuses on rheology of model cement pastes at an early age. The goal of this study is to better understand how chemical additives such as superplasticizers modify colloidal interactions, which control the behavior of fresh cement pastes. To this end, we use a model material (monodisperse silica particles) having controlled properties to prepare pastes with and without superplasticizers. By combining rheometry tests and experiments with laser tweezers, we try to link the rheological properties of these pastes to the contact properties between particles. This fundamental understanding can help to better control the formulation of cementitious pastes used in industrial processes.<\/p>\n

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Xiaoyan Ma (2020 – 2021) : now Associate Prof. at Beihang University<\/h4>\n

Philippe Coussot<\/span><\/em>, Benjamin Maillet, Laurent Brochard, Olivier Pitois<\/em><\/p>\n

Hello! I\u2019m Xiaoyan MA. After obtaining my doctor degree in University Paris-Saclay (ENS Paris-Saclay ), I joined Philippe Coussot in October 2020 as a postdoc (funded by LabEx MMCD), in collaboration with Benjamin Maillet, Laurent Brochard and Olivier Pitois. Following my PhD work, which was on transfer mechanisms in porous media by experimental and numerical approaches, my current subject focused on the characteristics of bio-sourced materials. Such as cellulose, there exist considerable potentials of applications in many fields as biomass, construction and recycling material. We intended to give a better account of the effective properties and the physical mechanisms of transfers in such materials, which required to perform controlled experiments and got access to important internal characteristics like bound water content. It was essential to understand the moisture transfer phenomena, including drying and imbibition process. The investigation methodology contained several aspects: sorption, evaporation, diffusion by macroscopic operations and NMR\/MRI manipulations, mechanical associated measurements, and numerical simulations.<\/p>\n

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Anatole Geffrault<\/a> (2019 – 2022) : Now at Microfluidics Innovation Center<\/h4>\n

Philippe Coussot<\/span>, Hela-Bessaies-Bay (CPDM), Nicolas Roussel (CPDM) <\/em><\/p>\n

Hello! I started in 2019 my PhD work at Navier Lab with Philippe Coussot, and I am co-supervised by Hela Bessaies-Bey. I had discovered 3D printing of construction materials a year earlier during an internship in this lab and had loved the idea of being able to print my own house! My PhD aims at better understand how a paste (i.e. a yield stress fluid) flows out of a 3D printer and deposits on a surface, with an approach both experimental and analytical. By understanding what forces are applied on the filament being printed, and knowing the reological properties of the printed material, we should be able to predict the deformations taking place, and thus control the shape of the printed filament. This study, conducted on model materials like clay pastes, will help having successful 3D printings of construction materials such as concrete and raw earth.<\/p>\n

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Elisa Julien<\/a> (2019 – 2023) : Now at Saint-Gobain<\/h4>\n

Philippe Coussot<\/span><\/em>, David A. Weitz (U. Harvard)<\/em><\/p>\n

I joined Philippe Coussot as a PhD student in October 2019 to focus on fluid transfers in wood. My work is co-financed and shared between Navier Laboratory at ENPC and the Experimental Soft Condensed Matter Group at Harvard University. We intend to better understand water transfers such as imbibition and fluid exchanges between vessels, fibers and cell walls in hardwoods. The challenge is to develop physical models to master mechanisms at work for wood treatments, durability of wooden constructions, etc.<\/p>\n

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Hicham Dialla<\/a> (2019 – 2022) : Now at Scalian<\/h4>\n

Philippe Coussot<\/span><\/em>, Alban Gossart (CEA Marcoule)<\/em><\/p>\n

Hi everyone, I am Hicham. After I graduated from the Faculty of Science at the University of Aix-Marseille in Chemical Engineering. I joined Philippe Coussot as a Ph.D. student in October 2019. This Ph. D. is funded by The French Alternative Energies and Atomic Energy Commission. The main purpose of the work is to determine the possibilities of decontamination of cement deeply contaminated by radioelements using the \u201cre-absorbent paste\u201d process. Some studies with model porous systems (see Nidal) have shown that this process is efficient when there is little or no ions adsorption. I focus on understanding how does the process work with cementitious materials. I am looking at the role of the cement reactive sites, and in particular the sorption and desorption reactions. I also study the transport of water (imbibition, drying, fluid exchange with the paste) by using an original technique developed at the Navier Laboratory and which consists of following the evolution of the distribution of NMR relaxation times in the studied sample, giving us more information on how water has penetrated the different pore sizes of the material. In addition, MRI scans of these samples can be used to evaluate the penetration depths of water into the material. My co-supervisors at CEA are Alban Gossard and Jean-Baptiste Champenois, and I work on MRI with Benjamin Maillet in Laboratoire Navier.<\/p>\n

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Fadoul Oumar Abdoulaye<\/a> (2018 – 2021) : Now at Valobat<\/h4>\n

Philippe Coussot<\/em><\/span><\/p>\n

Our interest is in the instability of Saffman-Taylor for yield stress fluids in porous media. One studies here the possible viscous digitation of circular samples moved radially in a Hele Shaw cell (which consists of two plexiglass plates whose spacing between the two is weak in front of other dimensions). This flow is the 2d analogue of a flow in a porous medium. For a Newtonian fluid one knows that the instability occurs beyond some velocity of the interface. Below this speed the interface remains circular. Two modes of flow are however then observed: beyond a critical velocity the air penetrates in the form of fingers through the material; the fluid leaves traces on the walls, indicating that in these zones it is sheared. Below this critical velocity the air region grows bigger regularly but the interface is still unstable, deformations resembling fractures are observed at various points of the interface.<\/p>\n

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\u00c9lie N’Gouamba<\/a> (2017 – 2020) : Now at Sintef<\/h4>\n

Philippe<\/span> Coussot<\/span>, Julie Goyon
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Hi ! My name is \u00c9lie, I am currently a a R&D project leader at SINTEF in Norway. My work revolves around drilling and oil-well materials, the structural integrity of the wells and carbon (CO2) storage and capture. From 2017 to 2020, I have worked with Pr. Coussot and Dr. Goyon on the rheological properties of several yield-stress fluids (carbon black suspensions, clays, emulsions, xanthan gum, …) with an emphasis on the solid regime. I was tasked with fluid formulation, rheometry, MRI and modelling. During my free time, I enjoy reading about theology, to travel around the world, and running.<\/p>\n

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Thibault Lerouge<\/a> (2016 – 2020) : Now at Valobat<\/h4>\n

Philippe<\/span> Coussot<\/span>, Olivier Pitois, Daniel Grande (ICS Strasbourg)<\/em><\/p>\n

Hi ! After graduated from Chimie ParisTech, I started in October 2016 my Ph.D. about multifunctional bio-based porous materials for sustainable construction (funded by LabEx MMCD). This project intends to understand the impact of a double porosity on some transfer and mechanical properties of porous media. Polymers materials with biporous network are designed as a reference system for multi-scale building materials, and elaborated with Daniel Grande, Co-director of Complex Polymer Systems team, (ICMPE Thiais \u2013 CNRS), whilst the physical properties research is supervised by Olivier Pitois (Navier) and Ph. Coussot in Laboratoire Navier. Those materials aims to become bio-based with various surface specificities.<\/p>\n

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Francesco Bonacci<\/a> (2016 – 2019) : Now postdoc at University of Perugia<\/h4>\n

Xavier Chateau, Tarik Bourouina (ESYCOM)
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Dense colloidal suspensions (or pastes) constitute a broad class of materials found in areas ranging from environmental systems (e.g. silts, clays), to industry (ceramics, drilling muds, slurries), construction (plaster, cements), foodstuff, cosmetics, pharmaceuticals (toothpaste, medical ceramics). Their most remarkable feature is thixotropy: a slow evolution of their mechanical properties when switching from rest to flow (at fixed density, in the absence of drainage). At rest, it is usually accompanied with aging—slow, non-exponential dynamics at long times. In cements, the formation of hydrate gels between grains, which determines the late-time strength and mechanical properties of solid concrete, was proposed to play a role in thixotropy. Yet it remains unclear how solid-solid contacts may affect just the elastic modulus of colloidal systems. Previous experiments have led us to ask whether the evolution of particle contact bending stiffness could be responsible for mechanical aging in pastes, without invoking changes in the network structure. This work aims to investigate the potential existence of a link between contact and macroscopic aging, by combining measurements performed at the particle level, through optical-trap three-point bending tests and confocal microscopy, and at the macroscopic scale, through rheometry.<\/p>\n

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Asmaa Kaddami<\/a> (2016 – 2019) : Now at N\u00e9olithe<\/h4>\n

Olivier<\/span> Pitois<\/span>, Vincent Langlois<\/em><\/p>\n

Hello! I\u2019m Asmaa Kaddami. I started my PhD with Pr. Olivier Pitois in October 2016, and my co-supervisor was Vincent Langlois. I worked on the elaboration of geopolymer foams with highly controlled morphology and the study of their functional properties. Geopolymers are an exciting class of eco-frienly binders used in various applications such as fire-resistance and thermal and acoustic insulation. Adding bubbles to these materials makes them even more exciting, and that was the first chapter of my work alongside investigating the stability of fresh geopolymer foam before its hardening. As a result, solid monodisperse geopolymer foams with controlled microstructure (pore size and air volume fraction) were produced. This enabled us to study transport properties in these materials, like air permeability, water imbibition and acoustics, and their dependency on foam morphology.<\/p>\n

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Xiao Zhang<\/a> (2015 – 2018) : Now at GE Healthcare<\/h4>\n

Philippe Coussot<\/span>, Tarik Bourouina (ESYCOM) <\/em><\/p>\n

Ketchup, mustard, shaving creams flow only when submitted to stresses
\ngreater than a critical stress \u2013 yield stress, these are yield stress
\nfluids. On smooth surfaces, these fluids can flow under very small
\nstresses; this phenomenon is the wall slip. Using gels, emulsions, clay
\nsuspensions, etc., and from rheometrical tests with original protocols
\nand internal measurements (MRI velocimetry), we show that a minimal
\nstress must be reached to initiate wall slip and, depending on cases,
\nthis value is either due to an edge effect or to an adhesion of the
\nsuspended elements to the wall. Above this critical value, the excess of
\nstress is found to vary linearly with the slip velocity, except at the
\ntransition of the yield stress or using a microtextured surface: in that cases the relation becomes quadratic. The wall slip can be interpreted as the shear flow of a thin liquid layer between the yield stress fluid and the wall. We also study wall slip under more complex flow conditions, by inducing an elongational flow during a traction test with smooth surfaces. The normal force measured for various materials with different microstructures shows that the yielding condition in an elongational flow is different from the standard theory, and the apparent thickness of the wall slip layer is several orders of magnitude larger than that found in shear flows.<\/p>\n

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Aymeric Mouquet<\/a> (2015 – 2018) : Now at Lebon<\/h4>\n

Olivier Pitois,<\/span> Tamar Saison (Saint-Gobain) <\/em><\/p>\n

Hello everyone, I\u2019m Aymeric. After I graduated from ENSC Rennes, I started my PhD in November 2015 with Saint-Gobain Recherche and Navier Laboratory. This work focused on studying foam films mechanics with a confined structure because of their low thickness. Using a precise microfluidic foaming method developed in Navier laboratory and based on aqueous polymer dispersion, we managed to generate controlled monodisperse, polydisperse and bidisperse structures. Thanks to the use of X-ray tomography along with mechanical characterization, we quantified the confinement-induced order and highlighted the particular mechanical behaviour of these different structures. This PhD project was funded by Saint-Gobain Recherche. I had the chance to work with Olivier Pitois, Yacine Khidas and Xavier Chateau in Navier laboratory and with Tamar Saison and Jean-Yvon Faou in Saint-Gobain Recherche. I am currently a research engineer at Lebon Group.<\/p>\n

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Blandine Feneuil<\/a> (2015 – 2018) : Now at SINTEF<\/h4>\n

Olivier Pitois<\/span><\/em>, Nicolas Roussel (CPDM)<\/em><\/p>\n

Hi ! I started my PhD in 2015 with Olivier Pitois and Nicolas Roussel to work on cement foams. I prepared highly controlled samples, with all bubbles of the same size and measured their rheological properties. My main objective was to understand how to optimize cement paste formulation to obtain stable samples, i.e. to avoid bubbles growth and migration. After my PhD, i decided to keep on working in rheology by doing a postdoc at the University of Oslo. My project deals with drilling fluids; I investigate experimentally particle sedimentation in emulsions. I am currently a research engineer at SINTEF (Norway).<\/p>\n

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Meng Zhou<\/a> (2015 – 2018) : Now at Hutchinson Japan<\/h4>\n

Philippe<\/em> Coussot<\/em><\/span>, <\/em>Sabine Car\u00e9 (MSA), Denis Courtier-Murias (Leesu), Pam\u00e9la Faure, St\u00e9phane Rodts<\/em>
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Hi, I am Meng ZHOU, I joined Pr. Philippe Coussot\u2019s research group in Nov. 2015 after graduating from EPSCI Paris. Following my PhD defense, I am now working for Saint-Gobain as a R&D engineer based at NIMS (National Institute of Materials Science) in Tsukuba, Japan. My job is to support company\u2019s research centers across the world with NIMS cutting-edge technologies in the materials science field by launching collaboration projects. My PhD work focused on water transport mechanisms in wood. Water transfers such as imbibition and drying were studied with different methods. The main results of our work showed that the dynamics of water imbibition in wood is significantly different (3 orders of magnitudes slower) from Washburn\u2019s law in a classical porous medium. With the help of advanced imaging techniques such as MRI and 3D tomography, this observation was interpreted by the evolution of wetting properties as a function of bound water content in cell-walls. Similar observations were obtained in a hydrogel-based \u201cartificial\u201d wood supporting our hypothesis. My co-supervisors were Sabine Care, Denis Courtier-Murias, Pam\u00e9la Faure and St\u00e9phane Rodts.<\/p>\n

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Yousra Timounay<\/a> (2013 – 2016)<\/h4>\n

Florence Rouyer,<\/span> Elise Lorenceau (LiPhy)<\/em><\/p>\n

My work consisted in developing solutions to characterize and study fluid-fluid interfaces, foams and emulsions. During my postdoc in the Physics department at Syracuse university (2017-2019), I worked on pattern formation in compressed ultrathin elastic sheets confined to a liquid-air interface in a curved environment. Prior to that, I did my PhD thesis at Laboratoire Navier (2013-2016) where I studied the rheology of liquid-air interfaces, soap films and soap bubbles loaded with solid particles.<\/p>\n

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Benoit Laborie<\/a> (2012 – 2015) : Now at Sweetch Energy<\/h4>\n

Florence Rouyer<\/span><\/em>, Dan Angelescu (Fluidion), Elise Lorenceau (LiPhy)<\/em><\/p>\n

Since 2017, I work in R&D in a start-up coming from the Micromegas team (ENS\/IPGG) named SWEETCH ENERGY. The project aim at scaling-up an energy harvesting technology. From 2015 to 2017, as a postdoc at ENS in Laboratoire de physique statistique and institut Pierre Gilles de Gennes (Micromegas team), I did mostly experimental investigation of various nanofluidics systems for different applications (kidney-on-a-chip, biphasic separation, energy harvesting), membrane fabrication, and electrochemistry. I did my PhD thesis at ESIEE Paris (ESYCOM) and Laboratoire Navier (rheophysic team) from 2012 to 2015, and I studied the possibility of using microfluidics based technique to produce controlled yield-stress fluid foams. My advisors was Florence Rouyer, Dan Angelescu and Elise Lorenceau. Prior to that, I had a Master’s degree in Fluid Dynamics (UPMC).<\/p>\n

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