WorldCat Identities

Jay, Pascal

Overview
Works: 8 works in 10 publications in 1 language and 15 library holdings
Roles: Thesis advisor, Opponent, Other, Author
Publication Timeline
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Most widely held works by Pascal Jay
Approches expérimentale et numérique de l'écoulement de fluides à seuil de contrainte autour d'obstacles cylindriques by Dodji Léagnon Tokpavi( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

The hydrodynamic governing a great number of industrial applications - in which yield stress fluids are used - has been investigated in this of work. The basic fluid mechanics problem that is the fluid flow around cylindrical obstacles is especially studied. Firstly, the case corresponding to very high Oldroyd numbers that is very little approached in the literature has been examined by extending the study to kinematics and dynamics aspects. Inertial effects are negligible. The case of one cylindrical obstacle and that of two cylinders in interaction are studied by numerical simulations. The results concerning rigid zones, stability, viscoplastic boundary layer are presented as a function as Oldroyd number. The case of one cylinder has been examined experimentally by drag measurement and flow characterisation by particle image velocimetry. The yield stress fluid used has been the subject of an in-depth rheometrical characterisation. Experimental results allowed to compare the elastoviscoplastic behaviour of the used gel to the results obtained with existing viscoplastic laws. In a second time, inertial effects were taken into account. An experimental study was undertaken on the flow around a cylindrical obstacle plunged in a rotating tank. This study, completed by numerical simulation, allowed to identify the effects of plasticity, shear-thinning and elasticity on the wake behind the cylindrical obstacle. The recirculation zone in the laminar steady regime and the transition between this regime and the one of laminar vortex shedding was specially examined
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
Études numérique et expérimentale de l'instabilité de Rayleigh-Plateau : Application aux jets d'encres by Maxime Rosello( )

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

Rayleigh-Plateau instability is used in continuous ink jet (CIJ) printers in order to drive ink jets breakup. Studies of such mechanisms are based on pluri-disciplinary concepts dealing with fluid mechanics, rheology and polymer sciences. The present work focuses on fluid properties and nozzles designs influences onto breakup dynamics. In this context, the experimental characterization of ink physical and rheological properties are of particular interest. Thereafter, jet dynamics computations are performed using several software and compared with experiences. Potential non Newtonian behaviours such as shear-thinning or viscoelasticity are modelled by computations. A close link between breakup dynamics and velocity profile at the nozzle exit is highlighted. This link is believed to bring crucial information for the prediction of jet dynamics observed in industrial printers
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

La convection de Rayleigh-Bénard est étudiée expérimentalement dans une cellule circulaire. Des fluides à seuil modèles (gels aqueux de Carbopol) sont mis en œuvre. Leurs comportements rhéologiques et leurs perméabilités en relation avec leurs microstructures ont été finement caractérisés. Dans toute la thèse, les expériences ont été menées sans glissement à la paroi. L'influence du seuil d'écoulement et de la distance entre plaques chaudes et froides sur les transferts thermiques a été approfondie. Trois mécanismes sont discutés pour expliquer le déclenchement de la convection: i) les propriétés visco-élastiques au-dessous du seuil, ii) le fluage au-dessous du seuil, iii) une approche d'un milieu poreux pour les gels de Carbopol considérés comme une suspension de micro-gels. On montre que le nombre de seuil Y, représentant le rapport entre la contrainte du seuil et la contrainte de la poussée d'Archimède est un paramètre important gouvernant l'apparition de l'instabilité. Les valeurs critiques de Y^(-1) sont déterminées entre 60 et 90. La visualisation à l'aide des cristaux liquides thermo-chromiques a permis une vue globale de la cinématique. Les structures observées dans les différents états thermiques montrent l'évolution de la convection. Une analyse qualitative du champ de température est également présentée. Enfin, la simulation numérique dans une cellule carré avec un modèle d'Herschel-Bulkley régularisé dans la gamme des nombres sans dimension utilisée dans les expérience a permis de mettre en évidence les paramètres critiques et la morphologie des champs thermiques et cinématique. Les ordres de grandeurs du nombre de seuil critique prédit se comparent raisonnablement avec les valeurs expérimentales
Etudes expérimentales et numériques des écoulements inertiels de fluides à seuil autour d'un cylindre by Stephane Mossaz( )

1 edition published in 2011 in French and held by 2 WorldCat member libraries worldwide

Creeping, recirculating and unsteady flows around a cylinder for yield stress fluid were studied.Numerically, morphologies of the flows, the location of the unyielded zones, the pressure and stress fields around the cylinder and the drag coefficient were determined over a wide range of Reynolds and Oldroyd numbers.Experimentally, fluids studied are polymer gels Carbopol®. The elastoviscoplastic behavior of these gels was modeled by a Herschel-Bulkley adapted law. The experimental setup was designed and validated by studying the flow of a newtonian fluid around a cylinder. An appropriate procedure for the viscoplastic fluid was implemented.We observe the influence of interface conditions with the appearance of a morphology showing simultaneous and symmetrical vortex shedding
Trainée et portance dans les fluides newtoniens et les fluides à seuil by Ziemihori Ouattara( )

1 edition published in 2018 in French and held by 2 WorldCat member libraries worldwide

This experimental and numerical thesis deals with the creeping flow of a Newtonian fluid and a yield stress fluid around a plate or a cylinder in the presence of a wall. The generated forces and the flow structures have been particularly studied. The study focuses for the yield stress fluid on large yield stress effects compared to the viscous effects. For the experimental approach, a device has been designed to measure simultaneously the drag and lift forces as a function of velocity and obstacle / wall distance. The fluids studied are a Newtonian glucose syrup and a Carbopol gel considered as a yield stress fluid model. These materials have been finely characterized from the rheological point of view. Numerical simulations using the Herschel-Bulkley anelastic viscoplastic model regularized by the Papanastasiou model were carried out. The results obtained with the Newtonian fluid allowed to validate the experimental set-up and the numerical approach. The effects of the yield stress, the wall / obstacle distance, the power law index and the inclined plate on the drag and lift coefficients were carefully examined. The lubrication regime has been studied for the cylinder both experimentally and theoretically. The morphology of the flow (rigid zones) and the local field quantities have been shown. Analytical solutions of drag and lift have been proposed. Comparisons between the experimental and numerical results as well as the solutions resulting from the plasticity of soil mechanics are analyzed. Deviations are discussed in terms of the elasticity and plasticity influence of the yield stress fluid
Solidification de fontes blanches au vanadium en coulée centrifuge : étude structurale et modélisation by Pascal Jay( Book )

2 editions published in 1991 in French and held by 2 WorldCat member libraries worldwide

L'OPTIMISATION DES PROPRIETES MECANIQUES CONCERNEES PASSE PAR LE CONTROLE DE DEUX ASPECTS PARTICULIERS DE LA STRUCTURE METALLURGIQUE: LA NATURE, LA DISTRIBUTION DES CARBURES ET L'ETAT STRUCTURAL DE LA MATRICE; LA MORPHOLOGIE, EN PARTICULIER L'ESPACEMENT INTERDENTRITIQUE. LES EQUILIBRES DE PHASE ONT ETE ETUDIES PAR ANALYSE THERMIQUE DIFFERENTIELLE ET CARACTERISATION. LES PARAMETRES STRUCTURAUX ONT ETE CALIBRES PAR SOLIDIFICATION DIRIGEE ET MESURES SUR LES PRELEVEMENTS DE CYLINDRES. UN MODELE DE SOLIFICATION A PERMIS LA CORRELATION ENTRE LES MESURES DE LABORATOIRE ET LES MESURES INDUSTRIELLES. LA CORRELATION S'AVERE SATISFAISANTE SEULEMENT SI LE REMPLISSAGE PROGRESSIF EST PRIS EN COMPTE
Simulation des Instabilites Thermoconvectives de Fluides Complexes par des Approches Multi-Echelles by Mohammad Saeid Aghighi( )

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

In this research work we are looking for two main physical and numerical purposes. The physical problem is to find the solution of Rayleigh Bénard convection for several conditions dependent on fluid thermo-physical properties such as temperature, viscosity and initial and boundary conditions. Continuing previous research works in this study we have provided the results of Rayleigh Bénard convection for Newtonian, Power-law and viscoplastic fluids (Bingham, Herschel-Bulkley and Casson) and for steady state and transient conditions. We also solve this problem for Nano and soft glassy materials. In some cases the results are interesting not only as a part of the Rayleigh Bénard convection analysis but also on a larger scale as a part of the heat transfer and mechanical fluid analysis such as viscoplastic and soft glassy material studies. Numerically, it was interesting to develop Proper Generalized Decomposition (PGD) method for solving transient coupled non-linear models, in particular the one related to the Rayleigh-Bénard flow. This model also was used to solve RBC problem parametrically by adding some physical properties as extra coordinates. For soft glassy material we used PGD to connect micro and macro equations together
 
Audience Level
0
Audience Level
1
  General Special  
Audience level: 0.95 (from 0.93 for Solidifica ... to 0.96 for Écoulemen ...)

Languages
French (10)