Дисертації з теми "Dispersion de liquide"
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Felis-Carrasco, Francisco. "Atomisation et dispersion d'un jet liquide : approches numérique et expérimentale." Thesis, Ecole centrale de Marseille, 2017. http://www.theses.fr/2017ECDM0001/document.
A typical water round-nozzle jet for agricultural applications is presented in this study. The dispersion of a liquid for irrigation or pesticides spraying is a key subject to both reduce water consumption and air pollution. A simplified study case is constructed to tackle both scenarios, where a round dn=1.2 mm nozzle of a length Ln=50dn is considered. The injection velocity is chosen to be UJ=35 m/s, aligned with gravity, placing the liquid jet in a turbulent atomization regime. The flow is considered statistically axisymmetric. Experimental and numerical approaches are considered.An Eulerian mixture multiphase model describes the original two-phase flow. Several U-RANS turbulence models are used: k-ε and RSM; where special attention is taken to the modelling of variable density effects from the mixture formulation. A custom numerical solver is implemented using the OpenFOAM CFD code. A series of study cases are constructed to test the influence of the turbulence modeling and first/second-order closures of the turbulent mass fluxes. LDV and DTV optical techniques are used to gather statistical information from both the liquid and the gas phases of the spray. The experimental campaign is carried out from x/dn=0 to x/dn=800. Concerning the LDV, small (~1 µm) olive-oil tracers are used to capture the gas phase, where a distinction between the liquid droplets and tracers is achieved by a specific set-up of the laser power source and the burst Doppler setting (BP-Filter and SNR). On the dispersed zone, DTV measurements are carried out to measure velocities and sizes of droplets. Special attention to the depth-of-field (DOF) estimation is taken in order to obtain a less biased droplet’s size-velocity correlation.Numerical and experimental results show good agreement on the mean velocity field. A strong dependence on the turbulence model is found. However, the RSM does not capture the same behaviour on the calculated Reynolds stresses. Indeed, neither the experimental anisotropy (R22/R11≈0.05), nor the liquid-gas slip-velocity can be reproduced, even with a second-order closure for the turbulent mass fluxes. The strong density ratio (water/air), flow’s directionality and production of turbulent kinetic energy may be the cause of a weak dispersion and mixing between the two fluids. This mechanism is not yet clarified from a RSM modeling point-of-view
Lobry, Emeline. "Batch to continuous vinyl chloride suspension polymerization process : a feasibility study." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/11498/1/lobry.pdf.
Wahl, Jacques. "Caractérisation d'une dispersion gaz/liquide par échos d'impulsions ultrasonores /." [S.l.] : [s.n.], 1987. http://library.epfl.ch/theses/?nr=590.
Dames, Maysoun Xuereb Catherine Azzaro-Pantel Catherine. "Gestion de procédés discontinus méthodologie de modélisation et d'optimisation d'opérations de dispersion liquide-liquide en cuve agitée /." Toulouse : INP Toulouse, 2005. http://ethesis.inp-toulouse.fr/archive/00000173.
Dames, Maysoun. "Gestion de procédés discontinus : méthodologie de modélisation et d'optimisation d'opérations de dispersion liquide-liquide en cuve agitée." Phd thesis, Toulouse, INPT, 2005. https://hal.science/tel-04582971.
Liquid-liquid dispersions and emulsions are formed in a large number of industrial domains, as well as in a wide range of products. However, their development presents one of the most complex operations. Dispersions are highly dependant on the physicochemical properties of products used and the hydrodynamics in the apparatus, which makes the prediction of the dispersion characteristics, and in particular, the optimization of the process, extremely difficult. This thesis investigates two types of liquid-liquid dispersions. Each type is discussed via separate case studies both created in an agitated vessel. The first case investigates an extraction operation, while the second concerns emulsions manufacturing, where by the drop size must be controlled. According to the nature and the complexity of the phenomena considered, two different approaches have been developed. In the first case, an experimental approach has been employed in order to optimize the yield in the purification step of a multi-functional acrylates process. The results show that there are predominant influences of certain operating parameters. It argued therefore that there is a need to develop a new process which considers environmental and economic requirements. In the second case, the development of emulsions with particular properties was investigated. The case adopts a synthetic approach that is based upon coupling a neural network and a genetic algorithm. Neural network is used as a non-linear modelling tool to determine the functional relationships between the means drop diameter and different operating variables. The genetic algorithm is used as a means for prediction the operating conditions that enable a given criteria (d32) to be reached. The application of these tools in the physical domain studied was shown to be of great interest. It is anticipated that such tools will lead to the development of new ways to control complex processes
Vu, Tuyet-Oanh. "Dispersion d'une poudre dans un liquide : caractérisation des interactions interfaciales et effets de différents facteurs sur la vitesse de dispersion." Saint-Etienne, EMSE, 2002. http://www.theses.fr/2002EMSE0029.
The aim of this work is to study a powder/liquid system for instantizing a powder in a liquid. The model powder chosen, cocoa, and its interaction with water were characterised to determine the dispersion behaviour. Contact angles and adhesion forces were measured by the sessile drop method and by a modified Washburm method. Water is a non-wetting liquid with respect to cocoa powder. Dispersion kinetics were measured by using an optical fibre detector. The most significant parameters on dispersion speed were the power of the agitation and the rise in temperature. Granulated powder was prepared by two processes : atomisation and high shear granulation. Atomisation lead to better dispersion while high shear granulation gave granules having an increased speed of dispersion
Kibboua, Rachid. "Etude d'une dispersion liquide-liquide soumise à un écoulement cisaillé simple : caractérisation vis à vis de la coalescence." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10167.
Segovia, Mera Alejandro. "Effets de la dispersion de nanoparticules dans un cristal liquide ferroélectrique sur les propriétés ferroélectriques et de relaxations diélectriques." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0461/document.
The present thesis work concerns materials made of dispersions of nanometric colloidal particles, from a bulk ferroelectric material, dispersed within a chiral smectic phase of a ferroelectric liquid crystal. The goal of this work is to study the effect of the dispersed nanoparticles over the nanocolloïd properties, specially the ones related to ferroelectricity. This study showed no change over mesomorphic and ferroelectric behavior of the materials. A decrease in spontaneous polarization and phase transition temperatures was found for low nanoparticle concentrations. A "transition" of these behaviors was observed for a critical concentration, beyond which, nanoparticles aggregate and form clusters inside the liquid crystal matrix. Afterwards, we have studied two dielectric relaxation modes. The first one related to distorsions of the helix in the ferroelectric phase and the second one to the compression movements of the smectic layers around the ferroelectric-paralectric transition. The observed behaviors seem to be due to modifications of the visco-elastic properties of nanocolloids, produced by intercalation of nanoparticles between the smectic layers
Rivière, Annise. "Granulométrie d'un liquide dispersé par explosif." Electronic Thesis or Diss., Ecole nationale des Mines d'Albi-Carmaux, 2024. http://www.theses.fr/2024EMAC0003.
As part of its studies on detonation, the CEA at Gramat is interested in the dispersion of liquids in air, with high speed/energy constraints and multi-scale aspects. Measuring the particle size of the dispersed liquid is attracting a great deal of interest, but is proving complex because no commercial solution can be used under these particular conditions. However, under these conditions and given the impossibility of using laser sources in a pyrotechnic environment, no commercial solution is available. For this thesis, a new granulometry identification method was developed, based on a measurement known as "extinction", which is particularly easy to deploy and robust in harsh environments. This is a multispectral approach (measurement with cameras or a spectrometer) using a regularised inversion method in the sense of Tikhonov, based on the measure of spectral transmissions and which makes it possible to reconstruct the granulometry of the latter a posteriori using the Beer-Lambert law combined with the Mie model. Given the complexity of the phenomena involved in using explosives for dispersion, the method developed was tested on liquid dispersions reproduced on a small scale on sprays. The general method was developed by exploiting spectral information from controlled water sprays confined in an enclosure placed in a Fourier transform infrared spectrometer (high resolution). However, as this equipment is poorly suited to field conditions, the measurement method was downgraded by using cameras that allow "low resolution" but faster measurements. The use of an infrared camera operating in the 2-5 µm spectral band with spectral filters and a flat black body was therefore tested to monitor changes in spray particle size as a function of time. This method was subsequently applied to water dispersions using explosives, with promising results. The complete measurement and analysis process was therefore validated at each stage of the study
Abdoune, Fatima-Zohra. "Dispersion de nano- et micro-domaines de cristal liquide dans des matrices polymères." Lille 1, 2006. http://www.theses.fr/2006LIL10163.
Mareuge, Isabelle. "Dispersion d'un scalaire passif dans un écoulement à bulles." Lyon 1, 1998. http://www.theses.fr/1998LYO10265.
Labégorre, Bernard. "Contribution à l’étude de l'influence d'une excitation acoustique intense sur la rupture et la dispersion d'un jet liquide." Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0230.
Mawlana, Abdulrahman. "Étude en régime permanent et transitoire du transfert liquide-gaz : cas d'un réacteur fluidisé gaz-liquide-solide." Toulouse, INPT, 1987. http://www.theses.fr/1987INPT026G.
Lin, Yaochen. "Dispersion de nanoparticules ferroélectriques dans un cristal liquide : élaboration, transitions de phases et propriétés diélectriques." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0443/document.
Liquid crystals are organic materials used to make electronic devices ; before using this material in applications, it is necessary to study their physical-chemical and dielectric properties in order to optimize their performance. This study is devoted to the nanocolloids obtained by dispersing ferroelectric nanoparticles in a nematic liquid crystal ; it means an inclusion influences the phase transitions temperatures and the dielectric properties of the host. The phase transitions measured by using Differential scanning calorimetry (DSC) evidenced the ferroelectric nanoparticles influence ; which is attributed two effects : the nanoparticles spontaneous polarization and the anchoring effect between nanoparticles and liquid crystal. The dielectric characterisation revealed the coupling between the macroscopic polarization of the inclusions and the electric field ; this coupling is manafested by an increase of phase transition temperatures compared to those determined by DSC. The competition between the polarization effect under an electric field and the anchoring effect induces a modification of the permittivities (parallel and perpendicular) and the dielectric anisotropy. Using harvested nanoparticles, the study confirmed the importance of the nanoparticles polarization to increase the properties of the studied nanocolloids. In fact, very small quantity of the harvested nanoparticles presents more significant improvements than those obtained with the non-harvested nanoparticles
Le, Guillaume. "Amélioration des propriétés choc d'une matrice polyamide-12 par dispersion réactive d'un élastomère liquide." Caen, 2001. http://www.theses.fr/2001CAEN2039.
Brunet, Léna. "Conception d'un nouveau type de colonne pulsée appliquée au contact solide-liquide." Toulouse, INPT, 2005. https://hal.science/tel-04582776.
This work deals with a novel type of pulsed column used as a solid/liquid contactor. An evolution in the design of the internals and in the shape of the pulsation has been set up. The initial objectives were to achieve a contactor of much longer solid residence time, independently of the liquid phase behaviour. Phase contacting is carried out countercurrently, solid is fed in at the bottom of the column and flows upwardly, regardless of the density difference between both phases. First, the technical feasibility was demonstrated. Then, the behaviour of solid and liquid phases was investigated through the analysis of residence times distributions. And, mass transfer efficiency has been evaluated with an industrial case. It was found that the column could enhance solid residence times, reduce granulometric segregation and solvent consumption. The new contactor seems to be particularly suitable for cases where a long contact between both phases is needed. Thanks to innovative internals and to an optimal tuning of the operating conditions, intensification of solid/liquid contacting was finally achieved
Mariaux, Sylvie. "Influence de la coalescence sur l'évolution granulométrique des dispersions liquide-liquide dans les écoulements turbulents en conduite." Grenoble INPG, 1990. http://www.theses.fr/1990INPG0037.
Sciolla, Dominique. "Extraction liquide-liquide sous champ électrique. Contacteur à électrodes externes." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1987. http://tel.archives-ouvertes.fr/tel-00845426.
Goalard, Carol. "Étude physico-chimique du procédé de dispersion des poudres libres et agglomérées en milieu liquide." Toulouse, INPT, 2005. http://ethesis.inp-toulouse.fr/archive/00000411/.
The dispersion of powders in liquids is a process widely used in industry and in every day life. The requirement to disperse a powder in a liquid rapidly and uniformly where the quality of the dispersion will define the quality of the final product. The optimisation of the process requires knowledge of the influence of the parameters on the kinetics of dispersion. To better understand the different energies involved, the process of dispersion may be divided into three stages : adhesion, immersion, and spreading. These stages can be examined as a function of the solid/liquid interfacial energy, the surface energy of the solid and the energy required to stir the liquid. A experimental device, with en optical fibre is used to characterise the dispersion. This technique allows the determination of the effects of various parameters on the operation
Goalard, Carol Dodds John. "Étude physico-chimique du procédé de dispersion des poudres libres et agglomérées en milieu liquide." Toulouse : INP Toulouse, 2007. http://ethesis.inp-toulouse.fr/archive/00000411.
Souidi, Kaïes. "Effet de la configuration des agitateurs dans une colonne à faible entrefer mécaniquement agitée sur la dispersion du gaz en foisonnement : approches expérimentale et numérique." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00836761.
Saint-Raymond, Hubert. "Étude de l'agglomération par turbidimétrie de poudres d'alumine en milieu liquide." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1995. http://tel.archives-ouvertes.fr/tel-00843295.
Castellano, Simone. "Multiscale study and modeling of dispersion properties relevant for liquid-liquid extraction : adaptation of breakup and coalescence kernels to industrial processes." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1243.
This PhD project deals with the study of the hydrodynamics of the dispersions in the liquid-liquid extractors employed in the nuclear recycle industry. In the first part of the project, a zero-dimensional homogenous Population Balance Model (0D-PBM), based on the evaluation of the volume-averaged coalescence and breakup rates, is adopted to fit low-viscosity turbulent liquid-liquid dispersion experiments. The method accounts for the spatial inhomogeneities in mixing, namely for the probability density function of the turbulent kinetic energy dissipation in the apparatus. In the second part of this study, a generalized model for the breakage and coalescence kernels, valid for the entire spectrum of turbulence, is proposed and validated. Most of the available kernels in literature indeed are based on the Kolmogorov second-order structure function, which is only valid in the inertial subrange. However, in many industrially encountered situations, most of the droplets may have size in the dissipation range, where the Kolmogorov second-order structure function does not apply. The generalized model is based on the Davidson second-order structure function, valid in the entire spectrum of turbulence. In the last part of the study, a model that allows to simulate the hydrodynamic behavior of a pulsed column is proposed. The model is based on a 1D Population Balance Equation (1D-PBE), whose source terms were modeled through the generalized Coulaloglou and Tavlarides kernels. The turbulent inhomogeneities in the pulsed column were accounted through the probability density function of the turbulent dissipation rate. The model well reproduces the experimental Sauter mean diameters and the dispersed phase volume fractions in a compartment of the pulsed column
Donnadille, Philippe. "Comportement de gouttes en écoulement turbulent instationnaire : simulation numérique, modélisation, experimentation." Valenciennes, 1992. https://ged.uphf.fr/nuxeo/site/esupversions/65515773-7bc6-415c-8beb-98e07fbcb3d7.
Sahraoui, Zoubida. "Contribution à l'étude des phénomènes de dispersion en zone stationnaire à partir de silices greffées de chaînes alkyles." Lyon 1, 1987. http://www.theses.fr/1987LYO19001.
Syaiful. "Réacteurs polyphasiques à cocourant ascendant : influence de la viscosité sur les rétentions, dispersions axiales et transfert gaz-liquide." Toulouse, INPT, 1992. http://www.theses.fr/1992INPT067G.
Adragna, Laurent. "MISE EN ŒUVRE REACTIVE DES POLYMERES :ETUDE ET MODELISATION DE LA DISPERSION EN MELANGEUR INTERNE D'UN LIQUIDE PEU VISQUEUX DANS UN POLYMERE FONDU." Phd thesis, Université Claude Bernard - Lyon I, 2006. http://tel.archives-ouvertes.fr/tel-00125596.
Adragna, Laurent. "Mise en oeuvre réactive des polymères : étude et modélisation de la dispersion en mélangeur interne d'un liquide peu visqueux dans un polymère fondu." Lyon 1, 2006. http://tel.archives-ouvertes.fr/docs/00/12/55/96/PDF/These_ADRAGNA.pdf.
The objective of this work is to build a model allowing the representation of the mixing phenomenon between two fluids having very different viscosities in an internal mixer, typically a cold plasticizer and a hot molten polymer. Experiments have been carried out through two different systems: ε-caprolactone with polycarbonate and polyamide 6. 6 with N-butylbenzenesufonamide, under different operating conditions. Then, we present a dynamic model based on a simplified view of the flow and on mass, energy and momentum balances. As far as the mass transfer is concerned, we consider simultaneously the mechanical action of the rotors and the diffusive process. Heat transfer has to be considered because of the important temperature difference between the two components and the viscous dissipation. Finally, a momentum balance allows us to calculate the velocity profile and the torque time evolution by considering that the viscosity is concentration and temperature dependant. A study on parametric sensibility has been done to measure the influence of parameters on physical data simulated. Simulation results will show a good agreement between the model and experiments
Adragna, Laurent Jallut Christian. "Mise en oeuvre réactive des polymères étude et modélisation de la dispersion en mélangeur interne d'un liquide peu visqueux dans un polymère fondu /." [s.l.] : [s.n.], 2006. http://tel.archives-ouvertes.fr/docs/00/12/55/96/PDF/These_ADRAGNA.pdf.
Daveze, Pascal. "Contribution à l'étude des propriétés magnéto-optiques des liquides magnétiques : applications opto-électroniques." Saint-Etienne, 1996. http://www.theses.fr/1996STET4008.
FOLIO, FREDERIC. "Dispersion centrifuge d'un alliage liquide soumis a un tres fort gradient thermique entre un plasma inductif et un disque froid tournant a tres grande vitesse." Clermont-Ferrand 2, 1994. http://www.theses.fr/1994CLF21648.
Zaborsky, Jiri. "Coalescence dans les écoulements laminaires : étude de drainage et de l'efficacité de coalescence." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0067.
Baraglia, Federico. "Développement d'un modèle triphasique Euler/Euler/Lagrange pour la simulation numérique des écoulements liquide-gaz chargés en particules." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP017.
This manuscript sums up work carried out during a thesis at the MFEE department of EDF R&D on liquid-gas flows laden with dispersed particles under the supervision of Olivier Simonin (IMFT), Jérôme Laviéville (EDF), and Nicolas Mérigoux (EDF). The thesis aims at providing a working environment for the numerical simulation of two-phase bubbly flows, free-surface flows or in a mixed regime, loaded with particles that can interact with the fluids present in their continuous or dispersed form. These flows can be found in industrial situations such as chemical reactors, power plants, or wastewater treatment plants, as well as in natural situations such as during a flood. The developed tool allows predictions to be made about the performance of these industrial devices or the damage caused by exceptional natural events. The developments are included in the most up-to-date version of neptune_cfd, a multi-fluid solver developed by EDF, CEA, IRSN, and Framatome, based on the standard multi-fluid method that allows the simulation of multiphase flow independently of their typology.The methods implemented are based on well-known two-phase approaches. The stochastic Lagrangian particle tracking method is adapted so that each particle can interact with all the fluids. Closures are proposed to determine the impact of each phase on the behavior of the particles. To verify certain assumptions, a new closure for the Langevin equation on the fluid velocity seen by the particle is proposed. Its behavior is compared to standard models and literature on simple verification cases of homogeneous isotropic turbulence and inhomogeneous cases. The Lagrangian equations obtained are used to close an Eulerian model based on the probability density function approach. The performance of the two developed threephase models is established in terms of particle deposition driven by turbulence or gravity.A significant part of the thesis focuses on an issue that arose during preliminary checks: the phenomenon of air entrainment in plunging jets. Indeed, due to the nature of the solver, bubbles or dispersed droplets can detach from the free-surface depending on the flow conditions. The quantity of these transferred structures and their characteristic size being crucial quantities which drives their behavior, a new model had to be developed. Mass transfer between continuous structures and dispersed inclusions is ensured by the model that describes the evolution of resolved interfaces, the latter was not modified. The one regarding the size of the created bubbles/droplets is integrated into the evolution equation of the interfacial area, a quantity that allows tracking the diameter of the inclusions.All developed models are compared to experimental measurements. The air entrainment model is first tested without the presence of particles in various cases. A hydraulic jump case is also considered to establish the generality of the model. Then, the threephase models are tested in various configurations. First, configurations without air entrainment to isolate the behavior of the particles, and then with air entrainment. The different cases highlighted the importance of certain models and the differences between stochastic Lagrangian and Eulerian methods
Quatravaux, Thibault. "Évolution de la modélisation du procédé VAR : contribution à la description de la dispersion inclusionnaire dans le puits liquide et à la prévention de défauts de solidification." Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL037N.
This thesis deals with the modelling of Vacuum Arc Remelting process (VAR) using the numerical software SOLAR. The first aim of the study is a better description of several physical phenomena which occur during melting, in order to extend the application of the software to simulate the remelting of steel. The evolution in the modelling of transport phenomena in the secondary ingot is based on three major improvements: - lateral thermal transfer modelling, in order to take into account the formation of a gap between the ingot and the mould walls, a possible injection of a neutral gas, and the heating of water in the coolant circuit, according to its flow, - a better turbulence model, since the k-E model implemented previously in the numerical code was not accurate enough to correctly descri~ the flow of the liquid metal in the pool, - a new method to simulate the ingot growth, based on a cyclic operation of splitting and growth/migration of control volumes, which reproduces the continuous growth of the secondary ingot and allows for the refinement of the mesh close to the free surface. Finally, the improved model has been validated by comparison with experimental results provided from four remeltings carried out on full-scale furnaces. The second objective is the characterization of the quality of the manufactured products in terms of inclusion cleanliness and risk of freckles segregated channel generation. Ln order to describe the behaviour of inclusions in the liquid pool, a trajectory model, adapted to account for turbulent flows, was validated and then implemented in the code. Various particle behaviours were distinguished. A study on the risk of freckles generation led to the establishment of a criterion particularly weIl adapted to the process. A generalization of this criterion, suggested in this work, would allow the prediction of the probable orientation of such segregated channels
Khalid, Perveiz. "Effects on seismic properties of thermoelastic relaxation and liquid/vapor phase transition." Pau, 2011. http://www.theses.fr/2011PAUU3002.
Two fluid-related sources of seismic attenuation and velocity dispersion are examined: thermal relaxation, which originates from the contrasted temperature variations in the rockforming minerals and in the saturating fluid at the passage of the pressure wave, and the liquid-vapor phase transition in partially saturated rocks, which consists in vapor condensation at pressure peaks and liquid vaporization at pressure troughs. An analysis of the relaxation times shows that these processes are relevant in the seismic frequency band and drive the effective fluid compressibility towards values higher than the unrelaxed values commonly adopted in practice, namely the adiabatic fluid compressibility in the first case, and Wood’s average of liquid and gas compressibilities in the second case. Under full thermal relaxation between fluid and mineral, i. E. , at low enough frequency, the effective fluid compressibility is equal to the average of the fluid adiabatic and isothermal compressibilities weighted respectively by the heat capacities of the fluid and the mineral. On the other hand, at the crossing of bubble point conditions, there is in the low-frequency or thermodynamic limit a discontinuous variation in fluid compressibility, whereas Wood’s average varies sharply but continuously. These features, analysed first by Landau and Lifshitz for pure fluids, hold for reservoir fluids as well. In these two relaxation processes, the difference in fluid bulk modulus between the unrelaxed and relaxed regimes, which is directly related to P-wave velocity dispersion, can be as large as 0. 5–1 GPa, depending on the fluid type and gas saturation
Verhaegen, Julien. "Modélisation multiphasique d'écoulements et de phénomènes de dispersion issus d'explosion." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10028/document.
This work focuses on modeling the formation and the dispersion of a cloud of droplets, induced by ejection of a liquid, resulting from an external aggression or an accidental situation. The goal is to build a model able to reproduce simultaneously the conditions which generate the cloud formation and the cloud evolution in time (dispersion). The main difficulty lies in the differences between the already existing models adapted to the description of flows which are able to characterize each stage of the global phenomenon: initially a multiphase flow model with compressible phases (Continuum), then the atomization and the formation of a cloud of droplets dispersed in a carrier phase (dilute flow model). We propose a new approach to achieve an effective coupling between these two models. The problem of the formation and the dispersion of the liquid requires to take into account several physical phenomena: atomization, heat and mass transfers and drag between phases. These phenomena are included in the global model through interaction terms involved in the systems of equations. The construction of this model has permited the realization of calculations describing the formation and dispersion of a cloud of droplets which may occur during, for axample, in accidental situations at industrial sites
Duplat, Françoise. "Refroidissement et dispersion du corium lors de sa chute dans l'eau pendant un accident sévère de réacteur nucléaire à eau pressurisée : description des interactions mécaniques et thermiques en écoulement triphasique lors de la dispersion de sphères solides froides ou chaudes dans un bain liquide." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0106.
Cardenas, Hector. "Étude de la pénétration et de la dispersion d'un jet triphasique solide-liquide-gaz dans un lit fluidisé en vue de la combustion de mousses chargées dans des foyers sous pression." Compiègne, 1995. http://www.theses.fr/1995COMPD813.
Gil-Díaz, Teba. "Comportement biogéochimique d’antimoine (Sb) et de tellure (Te) dans le milieu côtier : vers des scénarios de dispersion des radionucléides de Sb et de Te en cas de rejets accidentels de centrales nucléaires (projet AMORAD, ANR-11-RSNR-0002)." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0004/document.
Antimony (Sb) and tellurium (Te) are relatively uncommon contaminants (stable isotopes) and may form short-lived fission products (radionuclides) released into the environment during nuclear power plants accidents. Little is known about their respective biogeochemical behaviours, necessary for general contamination studies and post-accidental radiological risk assessment.This work provides original knowledge on Sb and Te biogeochemical behaviour in highly dynamic continent-ocean transition systems: the Gironde Estuary and the Rhône River. Concentrations, spatial/temporal variations, solid/liquid partitioning (Kd), and fluxes are studied from long-term records at the watershed scale. Four estuarine sampling campaigns during contrasting hydrological conditions show higher Sb solubility and Te particle affinity in the estuary than in the upstream fluvial reaches. Historical records (1984-2017) in wild oysters from the estuary mouth do not show clear trends of past or recent contamination, but measurable bioaccumulation suggests that potential uptake of radionuclides is likely to occur. Combined adsorption experiments using isotopically-labelled (spiked) Sb and Te, and subsequent selective extractions of carrier phases from suspended particulate matter (SPM) suggest that spiked Sb and Te are more mobile and potentially bioaccessible than their environmental (inherited) equivalents. Radiotracer adsorption experiments using environmentally representative concentrations of both Gironde and Rhône systems underpin that highly soluble elements may show contrasting reactivity between inherited and spiked forms.Radionuclide dispersion will greatly depend on (i) the geographical position of the source (Rhône) and/or the maximum turbidity zone (MTZ; Gironde fluvial-estuarine system), (ii) the succession of hydrological situations during and after the accident, and (iii) the biogeochemical reactivity and half-lives of the radionuclides. First scenarios on hypothetical dissolved radionuclide dispersion in the Gironde Estuary suggest (i) low sorption of Sb to the SPM, implying a transport of radionuclides in dissolved phase towards the coast, and (ii) high retention of Te within the MTZ, especially for accidental releases during flood conditions, linking the fate of radioactive Te to long estuarine SPM residence times (1-2 years). Potential upstream migration of Te radionuclides in the MTZ towards the city of Bordeaux during the following summer season and Te decay into radioactive iodine warrants further evaluation of the associated potential radiotoxicity
Plantamp, Alice. "Étude et modélisation du comportement chimique des aérosols issus d’un feu de sodium lors de leur dispersion atmosphérique." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0072/document.
As part of the development of 4th generation Sodium cooled Fast Reactors, studies are conducted on the consequences of a sodium fire, including the toxicological impact of possible releases of aerosols into the atmosphere. The carbonation of aerosols from a sodium fire results in a decreased toxicity, from their release point in sodium hydroxide (NaOH). The objective is to develop and experimentally validate a kinetics model of NaOH aerosols carbonation. The kinetic model based on the reactive absorption of atmospheric CO2 and using the double film theory enables to describe the carbonation of NaOH aerosols, initially formed as soda droplets. This model defines the initial aerosol characteristics of soda in equilibrium with the atmosphere. It is applied by considering the absorption of CO2 at the particle’s external surface. All the model variables are described and their equations explained. The validation of this kinetic model has motivated the development of an experimental device dedicated to the monitoring of physicochemical behavior of aerosols from a sodium fire with a better control of conditions of reactive atmosphere and of aerosols sampling. The new experimental data show the competition between the influence of temperature, partial pressure of water and of CO2. The comparison between the experimental results validates the kinetic model based on reactive absorption for relative humidity over 30%. Finally, the kinetic model was adapted into the form of an analytic expression for its use in association with the atmospheric dispersion calculation
Pierre, André. "Contribution des intéractions électriques dans les mécanismes d'adsorption des fluidifiants du ciment sur le dioxyde de titane et le carbonate de calcium : Application à la dispersion des particules." Besançon, 1988. http://www.theses.fr/1988BESA2012.
Thiriet, Maud. "Nanobâtonnets de NaYF4 à upconversion : synthèse, dispersion colloïdale et propriétés électro-optiques." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX071/document.
Fluorides nanoparticles doped with lanthanides have seen an increase in interest the last years. They offer outstanding optical properties with a very attractive upconversion for multiple applications from photovoltaics to medical imaging. In this work, we use NaYF4 nanorods doped with Yb/Er/Gd and optimized emission properties. Their alignment by an electric field allows us to access their anisotropic physical properties like polarized luminescence and birefringence.Nanocrystals are synthesized by a hydrothermal route, at high temperature (200 °C) and high pressure (20 bar). Morphology and crystalline structure can be controlled by varying gadolinium doping and heating conditions. At the end of the synthesis, the aggregation of the particles limits their dispersion in all common organic solvents. A particular functionalization with ligands having carboxylate or phosphonate functions is shown to be necessary. The grafting of particles with ions like citrate or alendronate allows to obtain very stable colloidal suspensions in DMSO. Furthermore, the reactivity of the amine function carried by alendronate enables us to graft a second active dye like rhodamine B or a cyanobiphenyl liquid crystal with a carboxylic group. New organo-mineral materials can be produced with this functionalization. The electro-optical response of colloidal suspensions submitted to a high-frequency electric field follows the Kerr law, with a quadratic relation between induced birefringence and the amplitude of the applied field. The system exhibits Kerr constants of the order of 108 m/V2, in agreement with the literature. The birefringence is induced by the anisotropic crystalline structure of the colloid, not by its shape. The mechanism of reorientation of colloids under an electric field is widely dominated by the polarization of their ionic cloud. A polarized luminescence is finally described, which will allow the use of NaYF4 nanorods as orientation probes in biological systems or fluid flows
Bucciarelli, Elia. "Liquid-liquid dispersion in mechanically agitated vessel." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Haam, Seungjoo. "Multiphase research on solid-liquid dispersion /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935958846755.
Razmislevičienė, Ina. "Dispersive liquid-liquid microextraction for the determination of metals." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130625_092031-65110.
Šioje daktaro disertacijoje apibendrintų mokslinių tyrimų tikslas – ištirti ir pritaikyti naujus Cr(VI), Co(II), Cu(II) ir Ni(II) koncentravimo ir nustatymo metodus apjungiant dispersinę skystafazę mikroekstrakciją (DSME) su lazerinio išgarinimo induktyviai sužadintos plazmos masių spektrometrijos (LA-ICP-MS) bei ultraefektyviosios skysčių chromatografijos (UESCh) metodais.
Salih, M. A. "Effects of antifoams on gas-liquid dispersion." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638752.
Thapar, N. "Liquid-liquid dispersions from in-line rotor-stator mixers." Thesis, Cranfield University, 2004. http://hdl.handle.net/1826/3316.
El, Hassan Zaki Mohamed Osman. "Modelling of liquid-liquid dispersions in batch stirred vessels." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46290.
Rajapakse, Achula, and s9508428@student rmit edu au. "Drop size distribution and interfacial area in reactive liquid-liquid dispersion." RMIT University. Civil Environmental and Chemical Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080717.163619.
Rodgers, Andrew Norman John. "Dispersion, assembly and electrochemistry of graphene at the liquid-liquid interface." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/dispersion-assembly-and-electrochemistry-of-graphene-at-the-liquidliquid-interface(c2ffd27a-cf5f-45c2-a471-60dcab788e12).html.