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The rheological and flow behaviors of Pickering emulsions are studied as a function of their water concentration. The studied emulsions are water-in-gasoil inverse emulsions stabilized with organo-hectorite clay. An in-line emulsion preparation was performed and a novel emulsification system was used. The emulsification system was tested and confirmed before performing pipe-flow measurements. A stress-controlled rheometer was used to study the rheological behavior of organoclay stabilized inverse emulsions. It was found that the emulsions exhibited a shear thinning with yield stress non-Newtonian rheological behavior and that the flow curves were well correlated using the Herschel-Bulkley model. Pressure loss and axial velocity measurements were studied to investigate the pipe-flow behavior of the emulsions. Axial velocity of the fluids was measured using an Ultrasonic Pulsed Doppler Velocimeter. It was shown that, up to 50 wt% water mass concentration, an exponential increase of yield stress and viscosity values is noticed, and the phase inversion point is not reached. In the range of the applied flow rates, turbulence took place only in the case of the lowest water cut (0 wt%). The Herschel-Bulkley rheological parameters were used to simulate the pipe-flow behavior of the studied fluids, and showed a satisfactory correlation with the in-line measurements. Furthermore, wall shear stress and velocity profiles were used to study the short-, medium-, and long-term stability of the emulsions.

The last step of activated sludge wastewater treatment consists in separating the residual particulate matter from water. This separation process takes place in a clarifier: a large tank in which sludge particles settle while clear water overflows. In order to improve numerical models of clarifiers, a better understanding of activated sludge settling mechanism is required. Laboratory batch settling experiments involving acoustic Doppler velocity measurement methods have thus been developed. The raw Doppler signal was recorded over durations of up to 22hours and then post treated. At the very beginning of the sedimentation process 3D turbulence produced by the initial stirring generates a high velocity standard deviation. 3D turbulence dissipates after a few minutes. Low amplitude fluctuations of the vertical velocity remain, whereas the average velocity decreases at any vertical location. Vertical velocity profiles exhibit two areas: an area of rising velocity in the lower part of the blanket and an area in which velocity fluctuates around a uniform settling velocity in the upper part. This last area decreases constantly and disappears completely after some minutes. A change in concavity of the rising velocity profiles after three hours rest indicates a change in the physical mechanism of consolidation.

The purpose of this paper is to investigate rheology and hydrodynamic behavior of different mass concentration of bentonite suspensions in pipe flow. Bentonite suspensions exhibited shear thinning and yield stress non-Newtonian rheological behavior. Most of the data reported are for the laminar and turbulent flow, data are also included the start-up flow development. The axial velocity distribution was determined using a Ultrasonic Pulsed Doppler Velocimetry technique. The experimental results show a progressive destructuration of the suspensions in the entrance region due to the segregation of the structural elements of the fluid and tend to a steady state and a fully developed laminar pipe flow. In the majority of cases, axisymmetric flow is observed for both laminar and turbulent flow conditions. Also an asymmetry characterizes the axial velocity profiles in the laminar-turbulent transitional flow. In the laminar regime, the flow parameters were fitted by using the Herschel–Bulkley model. For the turbulent flow, the Dodge and Metzner model was applied to fit the experimental data.

The addition of an increased amount of soluble fibre pectin in foods is desired due to its proven positive health benefits to human. The aim of this research was to explore the synergies between the commonly used food additives, carboxymethyl cellulose (CMC) and two types of pectin (high or low methoxyl, HM or LM) using rheological methods. The rheological properties of the reconstituted water solutions of the food additive powder were investigated, at different mass concentrations (0.05%–3.00%) and temperatures (4 °C, 20 °C, 37 °C and 60 °C), reflecting those of food storage and food consumption, using small and large deformation rheological measurements. Dynamic tests showed that CMC alone, HM and LM pectin alone and their combinations exhibit strong viscoelastic behaviour, under the conditions used in this study. For CMC solutions, the Cox–Merz rule was found to be obeyed to a reasonable degree at temperatures lower than the cloud point temperature. However, divergence from the Cox–Metz rule is observed when phase separation takes place. The current rheological methods are feasible to examine the synergy in viscosity and elasticity of mixed gel dispersion, which was determined by the polymer interactions via hydrophobic effects and hydrogen bonds depending on variables such as polymer substitution degree, polymer proportions and applied temperature.

L’objectif de notre travail est d’apporter un supplement de connaissance quant au comportement mecanique des boues biologiques en ecoulement. Pour ce faire, des fluides modeles ont ete mis en oeuvre. Il s’agit notamment de suspensions d’argile et de melange argile-polymere. Les fluides utilises sont une suspension de bentonite de concentration massique de 5 % et un melange de 5 %/0.1 % bentonite/carboxymethyl cellulose de sodium (CMC). Il a ete etabli que le comportement rheologique de l’argile et du melange peut etre caracterise par un modele a trois parametres de type Herschel-Bulkley. Un accent est mis sur l’effet de l’ajout de polymere sur les proprietes rheologiques et en ecoulement des boues. Cette etude est motivee, d’une part, par le fait que le polymere est un constituant de la boue elle-meme et d’autre part, par son utilisation comme additif pour le controle des proprietes physiques des boues. En regime laminaire les parametres d’ecoulement sont en accord avec les resultats analytiques obtenus a partir du modele de Herschel-Bulkley. En regime turbulent, les equations de Dodge et Metzner modelisent de maniere satisfaisante le comportement de ces fluides. Il a ete montre que le polymere a des proprietes viscosifiantes en regime laminaire, par contre en regime turbulent, il est un reducteur de frottement.

La rheologie apparait comme un champ d’etude primordial pour caracteriser le comportement des boues activees. Cette etude s’attache a tester differentes equations liant la viscosite d’une suspension de boues activees a sa concentration a l’aide de simulations numeriques de sedimentation en batch. Dans un premier temps, des echantillons de boues activees ont ete preleves dans une station de traitement des eaux afin d’effectuer des mesures rheologiques de maniere a obtenir des ordres de grandeurs realistes de viscosite ainsi que le rheogramme des boues. Celui-ci peut etre decrit par un modele de Bingham avec une bonne fiabilite.Par la suite, un modele tridimensionnel utilisant les equations de la mecanique des fluides couplees a la rheologie et la vitesse de sedimentation des boues a ete utilise pour simuler la decantation en batch dans une colonne cylindrique. Differentes relations issues de la litterature liant la viscosite des boues a la concentration ont ete testees : elles se distinguent essentiellement par des croissances plus ou moins rapides de la viscosite en fonction de la concentration.Les profils verticaux et les contours de concentration obtenus avec chaque modele sont compares. L’influence du choix de la loi de comportement rheologique est particulierement sensible au niveau de la distribution des concentrations au sein du domaine de sedimentation, l’irregularite des contours de concentration augmentant avec la fluidite de la suspension. Une simulation employant un des modeles precedents modifie de maniere a generer des valeurs de viscosite tres importantes tend a confirmer ce resultat.

Beverages are an ideal food format to deliver health-promoting polyphenols (PPs) and dietary fibres (DFs) to consumers. In this study, complex beverage systems, smoothies, were formulated containing high concentrations of apple PPs (500 mg per 300 ml beverage), apple fibres of two different particle sizes (AF01, 250 μm; AF09, 300–700 μm; each containing soluble and insoluble fibres), and stabiliser carboxymethylcellulose (CMC; 0.05–2.00 %). The beverages were pasteurised at 85 °C for 15 s, and subjected to total extracted PP content (TEPC) and rheological measurements (viscosity, elastic modulus G′ and viscous modulus G″ at 4, 20, 37 and 60 °C). Scanning electron microscopy (SEM), FT-IR spectroscopy and N2 physisorption measurements on the AF01 and AF09 fibre powders showed that they differed in particle size, yet were similar in particle surface morphology, chemical composition and specific surface area. Characterisation of smoothies prepared from the AF01 and AF09 fibres showed that the particle size of the apple fibres, testing temperature and CMC concentration strongly influenced the extractability of PPs and rheological behaviour of the smoothies. The peak TEPC values of the AF01 and AF09 beverages, 327 and 351 mg catechin equivalent per 300 ml beverage, occurred at 1.50 % and 1.00 % CMC, respectively. The temperature dependence of smoothie viscosity was examined, and an Arrhenius relationship was observed for both the AF01 and AF09 smoothie systems. The stabilising effect of CMC for this type of smoothie beverage was confirmed. CMC concentrations of 1.00–1.50 % afford high extracted PP content, good phase stability and beverage flow properties. These results presented here can be used to guide the development of stable beverages containing relatively high concentrations of PPs and DFs (including both insoluble and soluble).

L’objectif de notre travail est d’apporter un supplement de connaissance quant au comportement mecanique des boues biologiques en ecoulement. Pour ce faire, des fluides modeles ont ete mis en œuvre. Il s’agit notamment de suspensions de bentonite. A partir des mesures de profils de vitesses et des pressions, notre etude experimentale porte sur l’etude de l’evolution des parametres rheologiques des boues en ecoulement dans une conduite rectiligne. Nous etudions les profils de vitesse. Ces derniers sont caracterises par une zone bouchon au cœur de l’ecoulement et une zone cisaillee a la paroi. L’effet des singularites sur la destructuration des suspensions a ete mis en evidence. La mesure des viscosites montre le caractere rheofluidifiant des boues. L’etude des coefficients de frottement montre une evolution inversement proportionnelle au nombre de Reynolds en regime laminaire ainsi qu’une transition a la turbulence a partir de Re exp = 2050.

The rheological properties of aqueous solutions of poly(ethylene oxide) (PEO) of different molecular weights (1x10(5), 4x10(5), 1x10(6) and 4x10(6) g mol(-1)) and concentrations were investigated using shear viscosity and dynamic rheological measurements. It was found that the aqueous solutions of PEO do not exhibit a yield stress and that, above a critical shear rate, all PEO solutions exhibit shear-thinning behavior, well described by the Cross model, except for the solutions made by the lowest molecular weight (1x10(5) g mol(-1)) which were almost Newtonian. The parameters of the Cross model, namely the zero-shear rate viscosity and reciprocal of the time constant, allowed the determination of the critical concentrations c(*) and c(**) (respectively, the transition to semi-dilute network solution and concentrated solution). At concentrations higher than c(**) and below a critical shear rate, solutions made of PEO of high molecular weight exhibited a clearly shear-thickening behavior at very low shear rates. In addition, the dynamic tests showed that PEO solutions exhibit concentration-dependent viscoelastic properties, with a dominant viscous behavior at PEO concentrations lower than c(**) and a dominant elastic behavior at PEO concentrations greater than c(**).

Three different experimental measurements, namely, rheology, particle sizing, and x-ray diffraction (XRD), were used to study the effect of anionic additives on the properties of bentonite suspensions. The three additives were sodium carboxymethylcellulose, xanthan gum, and sodium dodecyl sulfate. Flow curves were obtained from shear stress–shear rate measurements, and the viscoelastic properties were determined from oscillatory and transient measurements. Mineralogical data were evaluated by XRD and the particle size analysis performed by light scattering technique. The presence of the surfactant modifies the face-to-face interactions and yields changes of the mixtures rheological behavior at low deformation rates. Polymers act by coating each clay particle and prevent their agglomeration. Therefore, the additives are responsible for the mechanisms of destructuration and structure reorganization as well as the mixtures viscous and viscoelastic behavior.

Malgre les connaissances geologiques accumulees sur plus de 800 puits carottes en continu au cours des quarante dernieres annees, le forage de la phase 8''1/2 du champ petrolifere de Hassi- Messaoud (Algerie) reste a ce jour delicat en raison notamment de problemes de cavage et de pertes de boue. L'objectif de ce travail etait d'etudier les problemes de pertes de boues en utilisant une approche sedimentologique et de localiser les niveaux producteurs sous-jacents du Cambrien. Pour cela, les zones a avancement rapide et lent des forages des series sedimentaires du Trias ont ete reperees afin d'en etablir des cartes de repartition. Ainsi, il a ete mis en evidence : - que les zones a avancement rapide correspondent aux secteurs sans pertes de boue (facies argileux de la plaine d'inondation), alors que les zones a avancement lent correspondent aux secteurs a pertes importantes (facies greseux des barres fluviatiles) ; - que sous les zones a avancement rapide dans les series du Trias, se trouvent des reservoirs d'hydrocarbures potentiels.

Bentonite are extensively used materials in a wide range of applications. Creep and oscillatory shear experiments in the linear viscoelastic domain were carried out on bentonite-water suspensions at different solid fractions. It was found that bentonite dispersions exhibit important viscoelastic behavior which could be represented by the generalized Kelvin-Voigt mechanical model. It is well known that an exhaustive study of colloidal dispersions may require the determination of its viscoelastic properties over a wide frequency scale. Unfortunately, due to microstructure changes, the experiments are limited in time. In order to avoid such limitation, oscillatory data were deduced from creep curves - without actually vibrating the clay dispersions - because a periodic experiment at frequency ω is qualitatively equivalent to a creep test at time 1/ω. That is, it was possible to complete the dynamic response in the low-frequency range using data obtained from the transient response in creep.

Le but de ce travail est d’etudier l’effet du polyethylene oxyde (PEO) (polymere non ionique), utilise generalement dans la formulation des boues de forage, sur le comportement rheologique de suspensions de bentonite. Des mesures rheologiques, granulometriques et zetametriques ont ete effectuees sur une suspension de bentonite, des solutions de PEO (polyethylene oxyde de masse moleculaire de 4.106, 106, 4.105 et 105 g.mol- 1) et des melanges bentonite-PEO a differentes concentrations de polymeres. L’etude a revele une forte augmentation (d’autant plus importante que la concentration et la masse moleculaire du PEO augmentent) de la viscosite, de la contrainte seuil et des proprietes viscoelastiques de la suspension argileuse. L’origine de ce changement de comportement a ete discutee sur la base de l'etude zetametrique et granulometrique. Cette derniere a mis en evidence des liaisons pont assurees par les chaines de polymeres entre les particules de bentonite. Mots cles : Boues de forage, bentonite, polyethylene oxyde.