WorldCat Identities

Laboratoire rhéologie et procédés (Grenoble)

Overview
Works: 33 works in 34 publications in 2 languages and 58 library holdings
Roles: Other
Publication Timeline
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Most widely held works by Laboratoire rhéologie et procédés (Grenoble)
Rhéologie et mécanique des fluides du conditionnement de produits semi-solides by Fanny Rasschaert( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

Packaging is a key step of cheese products industrial manufacturing process. It consists in filling containers of various shapes with non-Newtonian products while ensuring optimized rates. The aim of the present work is to describe the influence of cheese rheological properties as well as process parameters onto packaging, thereby contributing towards its optimization.Necessary for the study, the rheological behavior of cheese products on the process stress range at 80°C has been identified as shear-thinning with a yield stress, with elasticity both below and above the yield stress.Jets and filling hydrodynamics during packaging have been studied with three types of products by the means of the laboratory-scale process pilot, which is able to reproduce the industrial process conditions. After checking for consistency between experimental and litterature results for Newtonian products, the study focused on viscoplastic model fluids, Carbopol® hydrogels, and on cheeses.Five flow patterns have been observed and characterized through jet diameter, spread velocity during filling and final mound height after filling, which is a key factor of the packaging quality. Flow patterns dimensionless distributions have been determined from the forces involved in the system. Thus, the flow pattern can be predicted thanks to theses distributions from product rheological properties and geometrical and process parameters
Rhéologie des dispersions aqueuses thixotropes d'une argile de type hectorite by Frédéric Pignon( Book )

2 editions published in 1997 in French and held by 2 WorldCat member libraries worldwide

LE BUT DE CETTE ETUDE EST L'IDENTIFICATION ET LA COMPREHENSION DES MECANISMES GOUVERNANT LE COMPORTEMENT THIXOTROPE DANS LES DISPERSIONS AQUEUSES D'UNE ARGILE DE TYPE HECTORITE : LA LAPONITE. CETTE ARGILE MODELE, CONSTITUEE DE PARTICULES ANISOTROPES DE TAILLE NANOMETRIQUE, A PERMIS DE COMBINER LES MESURES RHEOMETRIQUES AVEC DES MESURES DE DIFFUSION DE RAYONNEMENTS, DES VISUALISATIONS DU CHAMP DE DEFORMATION ET DES MESURES DE BIREFRINGENCE. AU REPOS, LA STRUCTURE DES GELS EST CONSTITUEE D'AGREGATS MICRONIQUES DENSES ASSEMBLES EN UNE MASSE FRACTALE D'UNE DIMENSION D. PRES DE LA TRANSITION SOL-GEL, D = 1, LA TEXTURE EST FIBREUSE. AUX FRACTIONS VOLUMIQUES PLUS ELEVEES, D = 1,8, LA STRUCTURE EST UNE CONNEXION DE ZONES DENSES ET DE ZONES MOINS DENSES EN PARTICULES. DES LOIS D'ECHELLES THEORIQUES ET EXPERIMENTALES, ONT PERMIS DE CORRELER CES DIMENSIONS FRACTALES A L'INFLUENCE DE LA FRACTION VOLUMIQUE SUR LE SEUIL D'ECOULEMENT. LA TRANSITION SOL-GEL ET LA STABILITE DE LA PHASE GEL ONT ETE ETUDIEES EN FONCTION DU TEMPS DE GELIFICATION ET DES PARAMETRES PHYSICO-CHIMIQUES. L'EXISTENCE D'INSTABILITES D'ECOULEMENTS, TELLE QUE LA LOCALISATION DU CISAILLEMENT, ONT ETE MONTREES, SUR CES DISPERSIONS DONT LA COURBE D'ECOULEMENT EST A MINIMUM DE CONTRAINTE. LES DIFFERENTS REGIMES D'ECOULEMENTS ONT ETE IDENTIFIES ET ONT PERMIS D'ETABLIR DES PROCEDURES FIABLES POUR LA CARACTERISATION DU COMPORTEMENT THIXOTROPE. SOUS ECOULEMENT DE CISAILLEMENT, LA CHUTE DE VISCOSITE PROVIENT D'ORIENTATIONS ET DE DESAGREGATION A L'ECHELLE DE LONGUEUR DE L'ORDRE DU MICRON. LORS DE LA RESTRUCTURATION, LES DEUX ECHELLES DE TEMPS MISES EN EVIDENCE, CORRESPONDENT RESPECTIVEMENT A UNE RELAXATION RAPIDE DES ORIENTATIONS ET A UN PROCESSUS LENT D'AGREGATION. LA NATURE DU COMPORTEMENT THIXOTROPE EST ALORS IDENTIFIEE COMME ETANT PRINCIPALEMENT UN PROCESSUS D'AGREGATION REVERSIBLE, POUR LEQUEL LES GRANDES ECHELLES DE LONGUEUR, DE L'ORDRE DU MICRON, ASSOCIEES A UN ARRANGEMENT FRACTAL JOUENT UN ROLE DETERMINANT
Écoulements de fluides à seuil autour d'un cylindre en milieu confiné : études expérimentale et numérique by Hamdullah Ozogul( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

The flow of yield stress fluids around a circular cylinder in a confined geometry has been investigated with a Poiseuille flow configuration.Experimentally, a test set-up was built which provides a continuous flow in a closed loop. We studied creeping, recirculating and vortex shedding flow regimes. New results has been realised with a Newtonian fluid and Carbopol solutions, models for yield stress behaviour in laboratory experiments and in industry. A high speed camera and a laser sheet have been used to perform images which are treated by PIV. Kinematic fields, flow morphologies and critical transition parameters have been determined.Numerically, a viscoplastic model based on the regularised Herschel-Bulkley law has been used. Results as flow morphologies, rigid areas and local flow parameters fields have been performed. That allowed us to compare the intrinsic effects of Carbopol solutions and the viscoplastic numerical model. A specific study on the wall slip has also been considered with an elasto-hydrodynamic lubrication model
Rhéologie de suspensions hétérogènes concentrées : applications aux bols alimentaires et aux jus gastriques d'aliments solides. by Jeremy Patarin( )

1 edition published in 2014 in French and held by 2 WorldCat member libraries worldwide

L'enjeu des travaux contenus dans cette thèse est la caractérisation rhéologique de suspensions concentrées d'objets viscoplastiques suspendus dans une matrice viscoplastique. Trois contraintes physiques se présentent : l'hétérogénéité des objets, la taille des objets au regard de la taille du système étudié, et la proximité entre la consistance de la phase suspendante et celle des objets. Dans notre contexte alimentaire, il faut ajouter des contraintes d'ordre biologique : les faibles durées de vie des produits, les prélèvements in vivo et la conservation des conditions de températures et d'humidité. L'ensemble de ces contraintes aboutit à une rhéométrie spécifique, aux frontières de la mécanique des milieux continues, avec pour objectif de mesurer des propriétés rhéologiques pertinentes. Pour cela, deux instrumentations originales ont été construites pour effectuer la caractérisation rhéologique le plus vite et au plus près de la génération des échantillons.Appliquée aux bols alimentaires issus de fromage, leur rhéologie vient gouverner les écoulements en bouche et induire la création de surface d'échange en bouche, au travers de la mastication. Au travers de ces interfaces, les arômes et les sapides sont libérés et transportés vers les récepteurs sensoriels. Les résultats montrent le lien entre le seuil de contrainte à l'écoulement du bol et la libération d'arômes de différents hydrophobicités, fonction de la fermeté et du taux de matières grasses du fromage. Plus particulièrement, la phase suspendante fluide, semble jouer un rôle majeur dans la création et la persistance des surfaces d'échanges. Appliquée aux jus gastriques issus de pain, l'enjeu est de savoir si des modifications des contenus en glucides pouvaient impacter la rhéologie des jus gastriques, modifier les cinétiques de vidange en sortie d'estomac, et diminuer l'excursion glycémique. Les résultats montrent l'effet d'un ajout d'amylose sur l'augmentation de la viscosité aux temps de digestion longs, lorsque la rhéologie n'est plus gouvernée par l'encombrement des particules de pain gonflées d'eau. Cependant, l'amylose ne semble pas avoir d'impact sur les cinétiques de vidange, ce qui vient conforter que le débit en sortie d'estomac est régulé par la charge énergétique contenue dans le repas
Rhéologie des résidus agricoles pour un procédé multi-étapes de méthanisation en voie sèche by Victor Ruys( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

The Arkometha® process uses biogas injections to mix agricultural residues (manure, slurry, silage, straw) in a dry anaerobic digestion process. Knowledge of the rheological properties of these materials, rarely studied in the literature, and especially not on an industrial scale, is an essential element to supervise and control the mixing process. This thesis aims to improve the understanding of the physical and rheological evolutions of these materials along the anaerobic digestion process. The literature showed the need for a rheometer able to measure the rheological properties of these products at the industrial scale. For this purpose, specifications were established based on the scientific and technical constraints imposed by these materials, which are considered as fiber concentrated suspensions. On this basis, a large rheometer for substrates, called RGDS for (Rheometer Grand Dimensions for the Substrate), was built, validated and commissioned on an industrial site. The van test technique was used to measure the yield stress and mixer blades, calibrated using the Couette analogy, were used to measure shear stresses. In the third chapter we have shown the utilization limits of the total solids (TS%), traditionally used as the main parameter for rheology controlling. In this chapter we treated the yield stress of these materials as a rheological parameter example. We have shown that it is more appropriate to control the water distribution in order to control the rheological properties of theses suspensions by taking into account the spongy nature of the lignocellulosic material. We have shown how to determine the critical concentrations separating the semi-concentrated, concentrated, triphasic and the wet granular behaviors and their relationship with yield stress. In the fourth chapter, we studied the effect of changes in the anaerobic digestion operating parameters, such as fiber size, temperature and TS on the rheological properties of materials. Several models and empirical equations have been proposed to quantify the advantage of making changes in the operating parameters on the rheology of these materials
Conditions hydrodynamiques et organisation structurale dans le dépôt formé lors de l'ultrafiltration tangentielle : application à la bioraffinerie by Candice Rey( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

Membrane separation processes commonly used in several industrial applications, like bio and agro industries, waste water and clean water treatments, are more and more exploited in biorefinery. As an example, cross-flow ultrafiltration process shows a high potential in separation protocol of raw feed components like cellulose nanocrystals to produce biomass. This process is limited by the increase of particles concentration at the membrane surface, which conducts to phenomena named concentration polarization and fouling, which decrease the filtration performance. The PhD work objective is to bring a better understanding of the mechanisms involved in the formation of these phenomena. Two characterization methods covering length scales from nanometer to micrometer have been developed thanks to new designed tangential ultrafiltration cells allowing to link the ultrafiltration process to small angle X rays scattering and to micro particle image velocimetry. These measurement performed in-situ during ultrafiltration of nanocrystal celluloses and Laponite clay suspensions have allowed characterizing the structural organization and the velocity field within the concentration polarization layers. The correlation of these results with the rheological behavior properties of the suspensions, have permitted to access for the first time to the stress field within the concentration polarization and fouling layer during the tangential ultrafiltration process
Elaboration et caractérisation de membranes nanofibreuses electrospinnées : influence de la rhéologie des polymères, de la structuration du réseau de fibres et de ses propriétés mécaniques by Khula Ganhi jahsim Aljaber( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

Electrospinning, an original polymer process under high electric fields to produce a network of thin fiber having a micrometer diameter, is widely used for the synthesis of nanofibrous non-woven membranes. The fabricated electrospun membranes have a high porosity and a high surface to volume ratio. Indeed, they reveal much interest and have been much developed in the last decades, which paves the way for numerous applications such as sensing, tissue engineering or drug delivery. Current research aims to have fibrous membranes with a controlled architecture using various types of collectors.This thesis is part of a global and emerging project that focuses on the production of structured scaffolds nanofibers based on biopolymers and dedicated to the therapeutic strategy for the regeneration of soft tissues.In the present work, the first focus was to develop new biocompatible and bioresorbable materials composed of nanoscale fibers obtained by electrospinning. In addition, this study examined the influence of viscosity, concentration, and surface tension of PEO solutions on the obtained fibers. Further, the flow rate, applied voltage and environmental parameters (temperature and humidity) were also optimized in the course of nanofibers production.Biocompatible fibers have been obtained by using PEO. It is a linear polymer that consists of ethylene and ether segments [-CH2CH2O-]n. The ether oxygen allows this polymer to interact with other hydrophilic species, while the ethylene part participates in hydrophobic interactions. Due to its water solubility, non-toxicity and electrospinn ability, PEO has been used as an additive in biopolymer solutions to enable the formation of electrospun fibers. The mechanical strength of the PEO depended on the molecular weight, the conformation of the polymer chains and the fiber scale, the structure of the network.The second major effort of this thesis focused on the control of the mesh fibers. Such research activity is justified by the expected influence of the morphology of the fiber network on the mechanical properties of scaffolds and their biomimetic character that could favor the colonization and growth of the cells of the host tissue. The control of this structure has been achieved through the development of collectors.The objective of this project is making non-woven fibrous structures in uncontrolled architecture as well as non-woven with controlled architecture by using the electrospinning process. These fibrous structures are obtained from Poly(ethylene oxide), PEO, solutions with different concentration and molecular weight. The deposit of fibers is made on two types of collectors: a) Aluminum foil, b) micro-structured collector (dimension 3×3 cm). The morphological analyses of the membranes were investigated using scanning electron microscopy (SEM) and their mechanical properties were characterized by tensile test using the ARESG2 rheometer. The morphology of the electrospun polymer gradually changes from beads to uniform fibers with increasing polymer concentration and molecular weight. A comparative study of the morphological and mechanical (tensile test) properties, of both fibrous structures is performed. This study showed that it is possible to have a distribution of fiber forming a very uniform primitive cell in a network of dimension 3×3 cm. This structured network has a strain at the break more important than that for the network fibers, which are collected on Aluminum foil
Nanofibres de cellulose pour la production de bionanocomposites by Oleksandr Nechyporchuk( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

One of the main challenges in the context of biocomposites development is to replace petroleum-based materials with bio-based. Because of their natural origin, relatively high strength and the ability to form transparent products, cellulose nanofibers have a large potential for application in the composite materials. This work was focused primarily on the optimization of cellulose nanofiber production methods using biochemical and mechanical treatments, secondly on their rheological and structural properties in an aqueous medium and thirdly on the production of latex-based composites. The questions of homogeneous dispersion of cellulose nanofibers in the matrix and the interactions between these components for the purpose of matrix reinforcement are particularly addressed
Étude des propriétés thermodynamiques et dynamiques des polymères confinés en géométrie nanoparticules by Chourouk Mathlouthi( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

Étude du comportement d'ADN en solution et aux interfaces et le rôle de la dynamique micellaire et la rhéologie dans la libération contrôlée de médicaments by Lourdes Mónica Bravo Anaya( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Nowadays, the target for reaching a greater efficiency in DNA compaction processes, the innovation ofDNA sensors development and the study of changes in the interfacial properties generated between metalsurfaces and DNA molecules has become an area of great interest in bioengineering. This section of thethesis proposes the coupling of rheological, electrochemical and optical techniques to perform a detailedstudy of DNA molecules behavior in the bulk state of the solution and at the interface with two differentmetallic surfaces, as a function of parameters such as temperature, DNA concentration and electricpotential. Firstly, the rheological behavior of DNA/buffer solutions, as well as the evidence of the criticalconcentrations (C★ and Ce) is discussed from simple steady state and oscillatory dynamic shearexperiments. After studying DNA solutions properties, electrochemical and optical techniques are used toidentify structural changes in Au/DNA and Pt/DNA interfaces and to describe the arrangement of DNAchains in the electrochemical double-layer as a function of concentration and within each characteristicregime, i.e. dilute and semi-dilute regimes. The obtained response trough Electrochemical ImpedanceSpectroscospy (EIS), Modulation Interfacial of the Capacitance (MIC) and Surface Plasmon Resonance(SPR) techniques reflects an adsorption process of DNA molecules taking place onto the metal surfaces.Finally, by selecting DNA concentrations in the dilute regime, we studied the formation of chitosan-DNAnanoparticles with defined stoichiometry for gene transfer.The specific delivery of active ingredients, known as vectorization, has actually become a greatchallenge in therapeutic research. This process has been used to control the distribution of activeingredients such as proteins, genes for gene therapy and drugs, to a target by associating it with avector. Molecules for chemotherapy are frequently hydrophobic and require vectorization to betransported to the target cell. In this section of the thesis, we look up to understand the collectiveexchange dynamics (fusion and fission) between amphiphilic block copolymer micelles at the equilibriumand out of the equilibrium, and the exchange dynamics between these micelles (representing vectors)and the simplest model of cells (liposomes). We used a fluorescent technique with hydrophobic pyrenederivative to probe the fusion and fission of micelles at equilibrium. After characterizing amphiphilicblock copolymers structure and studying their dynamics in and out of equilibrium, we proposed a timescan fluorescence technique to quantify the collective vectorization dynamics between amphiphilic blockcopolymer micelles and liposomes. The effect of the variation of several parameters such as liposomeconcentration and a chitosan adsorption were investigated in order to control the vectorizationdynamics between these vectors and cells models
Etude expérimentale de la formation des biofilms sous conditions hydrodynamiques contrôlées by Ana Cecilia de Andrade Pinho Medeiros( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

In the aquatic environment, 90% of microorganisms are present as a biofilm rather than free-swimming cells. Biofilms may develop on most of humid surfaces, in particular, in porous media for their high specific surface area. Biofilm formation in porous media is very interesting subject for many scientific researchers, because of its relevance to many industrial processes such as water treatment, soil bio- mediation, oil recovery and CO2 storage. However, the development of the biofilm is not just a passive aggregation of bacteria cells. It involves biological, physical and chemical interactions with the bacteria's micro-environment. Several studies in macroscopic scale have shown that hydrodynamic conditions in porous media play an essential role on the dynamics of biofilm growth, which in turn affects hydrodynamic properties of porous media such as porosity, permeability and pressure drop. In this thesis we have developed an experimental device and an appropriate methodology for the characterization of biofilm's structure. An experimental study on the influence of fluid flow on the formation and structure of biofilms was performed using a bacterial strain Pseudomonas putida. Biofilms were grown in micro Hele-Shaw flow cell (in PDMS or PMMA) under laminar flows (Re=0.04~2) and fed continuously with a nutrient medium. Characterization of initial colonization was also carried out in order to examine the statistical variability and reproducibility of experiments. Biofilm formation on a solid support under a sheared flow (Re=0.04 (0.0021 Pa) and Re = 2 (0.094 Pa)) was evaluated after 24, 48 and 72h of development. Observations were made under a confocal laser scanning microscopes using fluorescent tag. 2D images were taken at different positions in the flow cell and used to perform a 3D reconstruction of biofilm's structure and an evaluation of its spatial distribution for an observation area of 12 *12mm². The results show that biofilms formation is not sensitive to initial colonization. A stratification of biofilm was also observed. The inner layer has a thin thickness (5~10 µm), but with a dense structure, while the outer layer show rather a filamentous structure. The ratio of volume fractions between these two layers varies from 3 to 12, depending on the formation time. This difference is more important in the case of low shear stress than that of high shear stress, which means that the upper part of the biofilm seems to be controlled by the hydrodynamic conditions. By analyzing the spatial distribution of the biomass, we found that after 48h, the biofilm present a significant heterogeneity and the volume fraction of biomass decreases after 72h for both two hydrodynamic conditions, which suggests probable detachments or erosions of biofilm. Concerning the growth kinetics, different apparent growth rates were observed for each observation time. These values are significantly below the growth rates observed in free culture medium. This result also indicates a possible effect of hydrodynamics on the growth of biofilm. This experimental study of biofilm formation in micro-scale allowed us to obtain the information on the biofilm structural and its apparent growth rate, as well as the hydrodynamic effect on its properties across several pores of the porous media. This scaling up makes it's possible to develop eventually mathematical models to simulate the evolution biofilm's morphology and its spatial distribution in the porous medium
Melt processing of cellulose nanocrystals : thermal, mechanical and rheological properties of polymer nanocomposites by Malladi Nagalakshmaiah( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

The low thermal stability and irreversible agglomeration issues are limiting to process the polymer nanocomposites using CNC as the reinforcing phase. In this context, thermally stable and highly dispersed CNC were prepared by green process (Aqueous based methods) like physical adsorption and surface modification. These two different Extrudable CNC was reinforced in to hydrophobic polymers. Ensuing polymer nanocomposites had a positive impact on the storage modulus, tensile strength, Young's modulus. Importantly, no evidence of micro aggregates in the matrix was observed in the scanning electron microscopy images contrary to non-treated CNC. Both the surface modification and adsorption are the water based methods and is an industrially viable solution. Also, it can be applicable at industrial level
Ecoulements de fluides à seuil autour d'obstacles by Fiacre Ahonguio( )

1 edition published in 2015 in French and held by 2 WorldCat member libraries worldwide

Many industrial processes include numerous complex fluids often presenting a yield stress. Those fluids can also slip when interfacial conditions are favorable. All these properties affect their flows around obstacles. This thesis aims to understand such flows in a domain where the flow velocities are so low that inertia effects can be neglected compared to viscous effects which are substantially low compared to plastic effects. It analyzes the influence of the velocity and the slip on the drag force and the kinematic fields of the creeping flow of a yield stress fluid around obstacles either with adhesive or slippery wall. The flow is analyzed in steady regime. The considered geometries are the disc, the sphere, the cone and the flat plate. The fluid used has an elasto-viscoplastic behavior which is modelled by the Herschel-Bulkley and Hooke models. This behavior has been characterized by rheometrical tests performed with adherence and slip conditions. The main non-dimensional number is the Oldroyd number, i.e. the ratio between plastic and viscous effects, which ranges from 10 to 200. The drag forces measurements have shown that regardless of the obstacle and the interfacial conditions, the drag coefficient decreases with the Oldroyd number before tending towards to an asymptotical value. This asymptotical value highlights that for high Oldroyd numbers the drag coefficient is no longer governed by the velocity but depends only on the yield stress and the characteristic section of the obstacle. A stability criterion for which the obstacle is held in suspension has been calculated from it. The kinematic fields determined by PIV have enabled to characterize the shape and the extent of the sheared and static regions. The drag forces and the kinematic fields measurements have enabled to quantify the contribution of the normal and tangential stresses in the total drag force. The wall slip significantly reduces the drag coefficient and also reduces the extent of the sheared zones. A numerical simulation has been performed with an elasto-viscoplastic model by means of a code using finite elements method with Lagrangian integration points in the case of an adhesive flat plane
Instabilité de Rayleigh-Bénard dans les fluides à seuil : critère de démarrage, expériences et modélisation by Chong Li( )

1 edition published in 2015 in French and held by 2 WorldCat member libraries worldwide

In this thesis, three main mechanisms proposed in a recent paper (Darbouli et al., Physics of fluids, 25(2) 2013) have been discussed to explain the onset of Rayleigh Bénard Convection in a yield fluid (Carbopol gels): i) the elasto-visco-plasticity behavior of the material below the yield stress, ii) a viscosity at low values of shear rates by creep measurements below the yield stress, iii) a microscopic viewpoint considering the fluid as a porous two phases system. No-slip conditions have been achieved for all the experiments. The results with different Carbopol gels have proved the importance of Y, the yield number which presents the report of the yield stress and the buoyancy effect, as the governing parameter. The critical value of Y^(-1) with no-slip condition has been found between 60 and 90. A visualization measurement with the utilization of thermochromics liquid crystals presents a global view from above. Different structures have been observed in different states of thermal conditions, which describe the evolution of the convection. For several cases the color of the liquid crystals can indicate the temperature field in the whole experiment cell. Numerical simulations with a Herschel-Bulkley model have also been discussed in this thesis. The dimensionless parameters are defined approaching the values obtained in the experiments, so that we can compare the numerical results with some of experimental ones
Procédés de séparation membranaire de colloïdes : caractérisation des mécanismes aux échelles nanométriques et intensification par ultrasons by Yao Jin( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

This thesis studies an ultrasonic assisted cross-flow ultrafiltration process from macro tonano scales. Different types of colloids were investigated: synthetic and natural clay dispersions,casein micelles (skim milk) and starch or cellulose nanocrystal suspensions. Firstly, flowproperties and the changes due to ultrasound (US) were investigated. Secondly, structuralorganizations at nanometer length scales in the vicinity of the membrane during filtration havebeen revealed for the first time by real-time in-situ Small Angle X-ray Scattering. The applied USincreased significantly the permeate flux of ultrafiltration by an enhancement factor of 1.6 to13.5, depending on the structural organization of the colloids. The applied US has led to threemain effects: a removal of accumulated particle layer, a partial disruption or no change of thenano-organization. Thirdly, thanks to the obtained concentration profiles, a modeling approachhas allowed a prediction of the permeate flux
Etude des propriétés de transport de mousse dans des modèles de milieux poreux by Alexis Mauray( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

In enhanced oil recovery (EOR), foams are injected in porous media to improve oil recovery efficiency. The objective is to limit viscous fingering thanks to the high effective viscosity of the foam at low capillary number Ca. Foam is produced by the co-injection of a gas and a solution of surfactants. This thesis focuses on foam formation and transport mechanisms in model porous media using a heterogeneous micromodel made in NOA. Foam formation is studied using two different approaches. The first one consists in studying a co-injection of two fluids thanks to a jet flowing in the center of the system. This experiment shows that the less wetting fluids is dispersed in the other one when the capillary number is higher than 10-5. A second set of experiments is conducted by injected a pre-formed train of big bubbles in model a porous media. The bubbles divide until they reach a diameter of the order of to the pore size, for high enough capillary numbers Ca. Besides, we studied the transport properties of foam in similar model porous media. Direct measurements show that the pressure drop induces by the flow can be at Ca=10-6 as high as 3000 times the pressure corresponding to water injected at the same injection flow rate. This ratio decreases with capillary number. An analysis of the preferential paths by direct observations shows that, for low relative gas flow rate, only a few paths are active. However, an increase of the capillary number or if relative gas flow rate leads to a homogenization of the flow in the medium. Thanks to different simple models of straight or wavy channels, we measure that the pressure drop induced by a single bubble is in good agreement with Bretherton's law, and scales as Ca2/3. However, in wavy channels the pressure drop due to a single bubble deviates from this prediction and exhibits a plateau at Ca lower than 10-4. In this regime, the motion of the bubble is usually intermittent. Finally, we focus on foam formation and transport properties in presence of oil. Our observations lead to the conclusion that for our setup and surfactant formulations, oil has a negligible influence
RhéoSpeckle : un nouvel outil d'étude du comportement multi-échelle des matériaux hétérogènes by Nabil Ali( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

This work tries to better characterize the behavior of homogeneous and heterogeneous materials under shear with a multi-scale approach (macro-meso-micro-scopic). To do that, we have developed an innovative setup by coupling a rheometer to a speckle imaging geometry witch is spatially and temporally resolved (RheoSpeckle). We validate our experience using two perfect materials: a solid and a pure viscous fluid. On a solid sample, we calculate the displacement field on the speckle images with a resolution better than 1 µm. we demonstrate than, the microscopic elasticity of this material. On a pure viscous fluid, we measured the nanoparticle's size with excellent accuracy. When a constant shear rate is applied, the velocity profile is measured with a time less than 1 s with a spatial resolution of 100 µm over 5 mm. The microscopic dynamic of a Brownian solution under shear is probed and the shear induced on the decorrelation of the intensity correlation function is studied. We show the capabilities of our experience using a concentrated solution of wormlike micelles. The linear rheology is studied using rheometric measurements and our speckle imaging system. Nonlinear rheology is studied using rheometric measurements (macro), but also by calculating the velocity filed and the intensity of speckle images (meso). With mesocopics measurements, the formation of shear banding is proved and characterized. Finally, the spatio-temporal relaxation (micro) of shear bands of this material is studied. We show for the first time the existence of two relaxations times after shear and that the relaxation of bands is relatively slow
La fibrinographie : une méthode multi-longueurs d'ondes pour la détermination de la structure du caillot en plasma by Carhel Dassi( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

The physiological role of the clot is to avoid excessive bleeding in the presence of a vascular breach. Once this function is filled, the clot must be able to be easily destroyed, so that it is not transported in the venous system and does not hamper blood circulation. The formation of a fibrin clot and its lysis are key processes of hemostasis, implying simultaneously the polymerization of the fibrinogen monomers in a fibrin fibers network, and the destruction of this constituted network.Although this network controls the physical and mechanical properties of the clot, its structure at scales smaller than the micron is poorly characterized. The main problem in the physical characterization of clot in clinical settings is the current absence of a quantitative, sensitive and reproducible measurement method.We demonstrated in this work, thanks to our method using several wavelengths, that the analysis of the visible spectra of light transmitted through a clot allows to determine simultaneously, quantitatively and in quasi-physiological conditions, several essential parameters of structure of the fibrin clot, namely the number of protofibrils per fibrin fibers, the radius and the density of fibers, and various times of clotting and lysis of the clot. This method was validated by the results with CV inferior to 6 % under all test conditions and various plasmatic profiles: normal, hypo / hyper coagulant and hypo / hyper fibrinolytic. This demonstrates the robustness and reliability of the measurement method when measuring both clotting and clot lysis.This spectrophotometric method was implemented on a modified automaton dedicated to diagnosis of patients presenting hemostatic disorders. The clinical information and the interests expected from this new test concern at the same time the quality of the fibrin network, its accelerated lysis or its resistance to fibrinolysis, and the resultant of the coagulo-lytic balance
Etude des ferrofluides et de leurs applications à l'intensification des transferts de chaleur par convection forcée by Wahid Cherief( )

1 edition published in 2015 in French and held by 2 WorldCat member libraries worldwide

Cette thèse a pour objectif d'étudier les performances thermiques et rhéologiques des ferrofluides sous champ magnétique pour des applications de refroidissement. L'approche adoptée dans cette thèse est de nature macroscopique, et est basée sur plusieurs études expérimentales. Cette caractérisation des performances des ferrofluides est focalisée sur trois aspects : i) étude de la rhéologie ii) étude de la convection forcée iii) étude la conductivité thermique. Différents outils de caractérisation correspondant à chaque domaine d'étude ont été développés. Dans le domaine de la rhéologie, une cellule magnétique a été construite et adaptée à un rhéomètre afin d'étudier le comportement rhéologique du ferrofluide sous un champ magnétique allant jusqu'à 0,8 T. Cette démarche met en évidence l'influence du champ magnétique et de son intensité sur les forces de cisaillement. Dans le domaine des transferts de chaleur, une boucle thermohydraulique pour l'étude de l'échange de chaleur en convection forcée avec une paroi à flux imposée sous champ magnétique a été mise au point. Ce type de dispositif permet l'étude de plusieurs paramètres liés à la configuration spatiale du champ magnétique appliqué, à l'effet de l'uniformité du champ sur l'intensification des échanges de chaleur. La compréhension et l'analyse de ces résultats sont consolidées par l'étude de la conductivité thermique du ferrofluide sous champ magnétique. Un banc a été mis en place et a permis de mettre en évidence l'influence de la température ainsi que de l'intensité du champ magnétique sur cette grandeur. Á l'issue de ces caractérisations, l'application des ferrofluides pour le refroidissement de composants électroniques de puissance est discutée par une mise en œuvre expérimentale. Ces essais ouvrent la voie pour de nouvelles recherches et permettent de mener des réflexions relatives aux domaines d'application des ferrofluides
Influence de la nature du fibrinogène sur la structure et la mécanique du caillot de fibrine by Xabel Garcia gonzalez( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

La formation du caillot de fibrine, processus clé de la coagulation sanguine, implique la polymérisation des monomères de fibrine en un réseau de fibres. Ce réseau contrôle les propriétés mécaniques du caillot et constitue le squelette sur lequel se base la cicatrisation. Si l'influence des conditions de réaction (pH, concentration, ...) est bien connue, le rôle de la composition du fibrinogène sur la structure de la fibrine est inexploré. Cet aspect pourrait être important pour les pathologies cardiovasculaires qui présentent toutes une structure de fibrine anormale.Nous avons étudié la relation entre la composition de plusieurs fibrinogènes et les propriétés structurelles nano- et micro-métriques ainsi que la mécanique des caillots de fibrine. La composition en protéines co-purifiées de ces fibrinogènes a peu d'influence, alors que le profil de polydispersité contrôle la structure multi-échelle de la fibrine. Des mesures de diffusion des rayons x, de spectrophotométrie multi-longueur d'ondes et de microscopie confocale ont mis en évidence que les fibres provenant des fibrinogènes monodisperses sont quasi-cristallines, droites et rigides. Les fibres provenant de fibrinogènes polydisperses sont, elles, beaucoup moins organisées, courbées, avec un module de rigidité faible. Enfin, les propriétés mécaniques de la fibrine ont montré que la réponse des caillots aux déformations, aussi que les scenarios de rupture, sont directement liés à sa structure et donc significativement dépendants du profil de polydispersité des fibrinogènes. Ces résultats ouvrent de nouvelles perspectives dans plusieurs domaines, que ce soit pour l'utilisation optimale des fibrinogènes pour les dysfibrinogénémies et hémorragies, mais également pour la reconstruction tissulaire, ainsi que la compréhension du lien entre la structure anormale des caillots et les maladies cardiovasculaires
 
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  Kids General Special  
Audience level: 0.96 (from 0.93 for Rhéologie ... to 0.96 for Ecoulement ...)

Alternative Names
Laboratoire de rhéologie (Grenoble)

Rhéologie et procédés (Grenoble)

UMR 5520

UMR5520

Unité Mixte de Recherche 5520

Languages
French (15)

English (6)