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See detailHydrodynamic systems used to assess surface fouling, soil adherence and cleaning in laboratory installations.
Detry, J. G.; Deroanne, Claude; Sindic, Marianne ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009)

Detailed reference viewed: 16 (6 ULg)
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See detailHydrodynamical and ecosystem modelling on an IBM SP/2
Beckers, Jean-Marie ULg; Grégoire, Marilaure ULg; Rixen, M.

in Procedings of the second annual MMARIE (1997)

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See detailHydrodynamical and ecosystem modelling on an IBM SP/2 (part II)
Elmoussaoui, A.; Grégoire, Marilaure ULg; Nomérange, P. et al

in Procedings of the third annual MMARIE meeting (1998)

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See detailHydrodynamical and ecosystem processes in ice-covered seas of the Southern and Northern Hemispheres
Goffart, Anne ULg; Hecq, Jean-Henri ULg

in Journal of Marine Systems (2000), 27

Preface of the 30th International Liège Colloquium on Ocean Hydrodynamics Liège, Belgium (May 4–8 1998) : Hydrodynamical and ecosystem processes in ice-covered seas of the Southern and Northern ... [more ▼]

Preface of the 30th International Liège Colloquium on Ocean Hydrodynamics Liège, Belgium (May 4–8 1998) : Hydrodynamical and ecosystem processes in ice-covered seas of the Southern and Northern Hemispheres. Issue of JMS edited by Anne Goffart and Jean-Henri Hecq. [less ▲]

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See detailHydrodynamics and bed stability at smooth-to-rough transitions. Experiments based on acoustic flow measurements
Duma, Diana ULg

Doctoral thesis (2016)

As reflected in the scale of large contemporary hydropower schemes, flowing water may carry huge amounts of energy. If not mastered properly, this energy may cause impressive channel erosion and local ... [more ▼]

As reflected in the scale of large contemporary hydropower schemes, flowing water may carry huge amounts of energy. If not mastered properly, this energy may cause impressive channel erosion and local scour. Therefore, one lasting concern in hydraulic engineering has been the stability of structures, riverbeds and riverbanks against flow erosion. Two main limitations of current understanding of riverbed and riverbank stability are highlighted: the first one is directly linked to the evaluation of the flow action, while the second one relates to the conceptual framework in which stone stability is evaluated. Since the standard approaches use the mean bed shear stress to quantify the flow forces, they may only apply under uniform flow conditions, for which the ratio of turbulence intensity to the bed shear stress remains almost constant and the influence of turbulence is therefore implicitly incorporated. For non-uniform flow, correction factors have been conventionally applied to account for the turbulence fluctuations; but this approach does not reproduce the physical influence of turbulence higher in the water column and can only be used as a rule of thumb. A new approach was initiated recently in literature. Instead of using the standard Shields parameter, it quantifies the flow forces by means of a new set of parameters which combine explicitly the velocity and turbulence distributions over a certain water depth above the riverbed, while remaining reasonably accessible for engineering applications. Next, this quantity is related to a mobility parameter, which describes the bed damage. This new approach requires additional high quality experimental data to confirm its validity for a wider range of non-uniform flow. In this research, the focus was set on a single canonical configuration, namely a smooth-to-rough transition. We take a preventive perspective by focusing on the flow and bed stability conditions before a scour hole starts to develop and we are interested in characterising the flow conditions to ensure bed stability, i.e. prevent the dislodging of bed material downstream of the structure. As a second specific objective of the thesis, we aimed at evaluating the feasibility of using acoustic techniques to properly estimate the new bed stability parameters proposed in literature in the last decade and draw conclusions on stone mobility at smooth-to-rough transitions. The experimental tests were conducted in two laboratory flumes, a horizontal bottom flume (6 m long and 15 cm wide) and a tilting flume (up to 4% slope, 20 m long and 50 cm wide), in which we measured the flow velocity at a 100 Hz frequency, using two different acoustic instruments: an Ultrasound Velocity Profiler (UVP) and a 3D Acoustic Doppler Velocity Profiler (ADVP). The measurements were done immediately downstream of the transition from smooth-to-rough. Two types of tests were undertaken. In the first type, the stones were glued with silicone on the flume bottom and velocity measurements were performed without stone motion. This enables measurements of the flow characteristics both below and above the threshold for inception of sediment motion, without perturbations induced by stone displacements. In the second type, the stones in the measurement area were laid on the bottom of the flume (i.e. not glued) and the number of entrained stones was recorded. The tests were conducted by varying (i) the grain size of the bed material (8 mm, 15 mm and 30 mm), (ii) the flow velocity (between 0.74 m/s and 1.16 m/s), (iii) the sediments density (1410 kg/m³, 1690 kg/m³ and 2650 kg/m³) and (iv) the configuration (quasi-uniform vs. smooth-to-rough transition). Indeed, for the purpose of comparison, a uniform rough bed (quasi-uniform configuration) was considered also, by replacing the smooth part of the bed with similar sediments as in the measurement area. After a specific signal processing, flow variables were derived from the measurements and were next exploited to evaluate several bed stability parameters, with the aim of correlating them with bed damage data obtained from dedicated experiments. The results showed no correlation between the bed damage and the bed shear stress or between the bed damage and flow turbulent kinetic energy. In contrast, when the flow action is described by both mean velocity and turbulence characteristics, a relative good correlation with the bed damage was observed. Nonetheless, these correlations appear only per subset of points corresponding to the same grain size and/or same material density or flume geometry. With a total of 45 hydraulic configurations for which the flow characteristics were measured and 66 (times four repetitions) tests in which the bed damage was observed, the present research ends up with a unique dataset, which may prove useful in various research such as for the validation of 2D-vertical and 3D turbulent flow and morphodynamic simulations. Another key outcome of the present doctoral research is a systematic comparison between measurements conducted with the UVP and the ADVP. The ADVP is deemed generally more accurate and reliable. Nonetheless, both instruments remain somehow complementary. We showed that, under certain conditions, the considered instruments have the potential to contribute to the assessment of bed stability in the considered configurations. [less ▲]

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See detailHYDRODYNAMICS IN A DISPOSABLE RECTANGULAR PARALLELEPIPED STIRRED BIOREACTOR WITH ELLIPTIC PENDULUM MOTION PADDLE
Collignon, Marie-Laure ULg; Droissart, Laurent; Delafosse, Angélique ULg et al

in Biochemical Engineering Journal (2015), 93

Stainless steel bioreactors increasingly fall behind to their disposable counterparts in pharma research as they do not require cleaning or sterilization. This led company ATMI LifeSciences to develop the ... [more ▼]

Stainless steel bioreactors increasingly fall behind to their disposable counterparts in pharma research as they do not require cleaning or sterilization. This led company ATMI LifeSciences to develop the “Nucleo™”. Original in design, this disposable bioreactor comprises a rectangular parallelepiped plastic bag stirred by a paddle revolving in elliptic pendulum motion. Studies covering this bioreactor showed good homogeneity of culture medium as well as good productivity for animal cell cultures. To further explain these good performances, the flow inside the “Nucleo™” had to be resolved. This paper focuses on the mean flow description, computed from stereo-PIV measurements performed in 20 verticals covering the whole volume of a 50 dm3 Nucleo™ bioreactor. As the flow is already turbulent in the chosen agitation conditions, its dimensionless mean velocity field does not vary with the paddle rotational speed. Mean flow pattern exhibits an axial symmetry – same flow is observed in opposite quarters of the tank – and can be described as a three-dimensional helix coiled on itself to form a distorted horizontal torus which covers the whole tank volume. Mean velocity value is on average doubled in the cone swept by the paddle, and its two horizontal components are twice higher than its vertical ones. However, mean velocity remains significant everywhere and, in particular, no stagnant area is observed in tank corners. Our results thus confirm previous studies observations. [less ▲]

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See detailHydrodynamics of long-duration urban floods: experiments and numerical modelling
Arrault; Finaud-Guyot, Pascal; Archambeau, Pierre ULg et al

in Natural Hazards & Earth System Sciences (2016), 16

Flood risk in urbanized areas raises increasing concerns as a result of demographic and climate changes. Hydraulic modelling is a key component of urban flood risk analysis. Yet, detailed validation data ... [more ▼]

Flood risk in urbanized areas raises increasing concerns as a result of demographic and climate changes. Hydraulic modelling is a key component of urban flood risk analysis. Yet, detailed validation data are still lacking for comprehensively validating hydraulic modelling of inundation flow in urbanized floodplains. ln this study, we present an experimental model of inundation flow in a typical European urban district and we compare the experimental observations with predictions by a shallow-water numerical model. The setup is 5 ll\X Sm and involves seven streets along each direction, leading to 49 intersections. Different inflow discharges and flow partitions were tested. The performance ofthe numerical model is assessed and the upscaling ofthe experimental observations to the field is discussed. [less ▲]

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See detailHydrodynamics of River Networks Computed with Two-dimensional Unsteady Flow Equations : Comparison ofNumerical Methods
Pirotton, Michel ULg; Pochet, Thierry

in Russel, T. F.; Ewing, R. E.; Brebbia, C. A. (Eds.) et al Computational Methods in Water Resources IX, Vol 1 : Numerical Methods in Water Resources (1992)

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See detailThe hydrodynamics of the Western Mediterranean Sea
Euromodel group; Nihoul, Jacques ULg; Beckers, Jean-Marie ULg et al

Report (1995)

Euromodel is devoted to process studies in relation to the description, understanding and simulation of the seasonal and mesoscale variability of the general circulation of the Western Mediterranean. Deep ... [more ▼]

Euromodel is devoted to process studies in relation to the description, understanding and simulation of the seasonal and mesoscale variability of the general circulation of the Western Mediterranean. Deep water formation drives the large cyclonic gyre observed in the northern basin. Some seasonal and mesoscale characteristics of the Northern, Tyrrhenian and Western Corsican Currents are specifies. The flow throuch the strait of Gibraltar is not hydraulically controlled. Potential vorticity conservation and changes in the meridional pressure gradients explain the formation of the western Alboran Sea gyre. Cyclonic eddies at its periphery are observed and modelled. The Almeria-Oran jet-front system is described in terms of geostrophic adjustment of Modified Atlantic Water and Mediterranean Water. Algerian eddies are linked to baroclinic instability of the current. A cyclonic circulation around the continental slope in the whole western basin is observed at depth. Upper ocean mesoscale variability is related to downward penetration of near-inertial motions as observed near the Catalan front. In the Balearic Sea, spatial and temporal variability of two shelf / slope fronts influences the large scale dynamics. The MAST 1 phase of Euromodel, initiales a numerical simulation of the Western Mediterranean : the sole forcing by the density gradients throuh the straites of Gibraltar and Sicily quaalitatively reproduces the basin scale cycloni surface and intermediate flows and the coastal currents. [less ▲]

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See detailHydrodynamics, mixing and mass transfer in baffled stirred tanks
de Lamotte, Anne ULg; Delafosse, Angélique ULg; Calvo, Sébastien ULg et al

in Proceedings of the 15th European Conference on Mixing (2015, June)

The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach ... [more ▼]

The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach. Three closure models are tested for the resolution of the RANS equations. When fully-developed flow field is reached, gas-liquid transfer is implemented with a local mass transfer coefficient estimated by the eddy cell model, and the temporal evolution of dissolved gas concentration is predicted.Hydrodynamic and mixing quantities as well as mass transfer parameters for the different turbulence models are compared with experimental data available for the same geometrical and operating features. A critical analysis of the prediction results allow to assess the models capabilities and to highlight the possible critical issues of the simulations. [less ▲]

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See detailHydrodynamik und reaktiver Stofftransport an Einzeltropfen
Kalem, Murat; Pfennig, Andreas ULg

in Chemie Ingenieur Technik (2007)

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See detailHydrodynamique et Architecture Navale
Hage, André; Rigo, Philippe ULg; Lapy, Matthieu ULg

in Journées scientifiques et techniques du CETMEF 2012 (2012, December 05)

State of art en matière d'hydrodynamique navale et architecture navale pour la navaigatio nfluviale

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See detailHydrodynamique et distribution de temps de séjour dans les lits bactériens
Crine, Michel ULg; Marchot, Pierre ULg; Schlitz, Marc et al

in Les réacteurs gaz-liquide et gaz-liquide-solide (1990)

Detailed reference viewed: 31 (1 ULg)
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See detailHydrodynamique et morphologie d'une bactérie filamenteuse dans un fermenteur à cuve agitée
Groslambert, Sylvie ULg; Blacher, Silvia ULg; Crine, Michel ULg

in Tribune de l'Eau (La) (2003), 56(622), 58-64

Afin d'étudier l'influence de l'hydrodynamique sur une bactérie filamenteuse, Actinomadura R39, nous l'avons cultivée dans un fermenteur de laboratoire de 5 litres à cuve agitée en faisant varier les ... [more ▼]

Afin d'étudier l'influence de l'hydrodynamique sur une bactérie filamenteuse, Actinomadura R39, nous l'avons cultivée dans un fermenteur de laboratoire de 5 litres à cuve agitée en faisant varier les conditions d'agitation. Les variables sont la vitesse de rotation et le type de mobile utilisé: turbines Rushton ou Intermig. Les deux mobiles se distinguent par leur géométrie et par les schémas d'écoulement qu'ils induisent dans la cuve. L'influence de l'hydrodynamique sur Actinomadura R39 est quantifiée par l'évolution de sa morphologie. Cette dernière est estimée par analyse d'images sur des échantillons prélevés lors des cultures. Parallèlement, nous avons caractérisé l'hydrodynamique du fermenteur dans un milieu artificiel reproduisant la rhéologie des fermentations en mesurant la puissance dissipée et en effectuant des essais de traceurs. Ces derniers sont utilisés pour la modélisation du fermenteur par un modèle compartimenté et le calcul du temps de mélange. Nous avons pu ainsi mettre en relation les modifications de la morphologie et des grandeurs caractérisant les écoulements dans le fermenteur. L'existence de corrélations entre les paramètres du modèle et la morphologie a également permis une validation de la signification physique de ce modèle. [less ▲]

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See detailHydrodynamique souterraine et vulnérabilité à la pollution des ressources en eau en zone urbaine tropicale : cas du bassin versant de Mingoa (Yaoundé-Cameroun)
Kouam Kenmogne, Guy Romain; Ntep, François; Rosillon, Françis ULg et al

Conference (2010, March 29)

Une étude conjointe visant la compréhension des phénomènes d’hydrodynamique souterraine et de vulnérabilité des eaux à la pollution a été menée dans le bassin versant de Mingoa situé dans le périmètre ... [more ▼]

Une étude conjointe visant la compréhension des phénomènes d’hydrodynamique souterraine et de vulnérabilité des eaux à la pollution a été menée dans le bassin versant de Mingoa situé dans le périmètre urbain de Yaoundé. Il ressort de cette étude que le comportement hydrodynamique dans ce bassin est étroitement lié aux fluctuations pluviométriques. La carte hydrodynamique de l’aquifère supérieur du bassin versant de Mingoa révèle deux types d’écoulements convergents et divergents avec les grands axes de drainage d’orientation globale NE - SW ; SE - NW et N - S permettant de délimiter des sites favorables à l’implantation d’ouvrages de captage des eaux souterraines. Les sources potentielles de pollution répertoriées sont nombreuses et variées (latrines, tas d’ordures sauvages,...). Les résultats des analyses physico-chimiques ont permis de constater que hormis la température, le potentiel d’hydrogène (pH), CO2 libre et l’azote ammoniacal, les valeurs des autres paramètres sont bien centrées sur les normes de qualité des eaux destinées à la consommation humaine prescrite par l’Organisation Mondiale de la Santé (OMS). Cependant, les valeurs des teneurs en en Streptocoques Fécaux (de 48 UFC/100 ml à 5,80 x 105 UFC/100 ml) et en Coliformes Fécaux (de 300 UFC/100 ml à 1,07 x 106 UFC/100 ml) sont largement supérieures aux valeurs seuils requises par l’OMS et permettent de conclure que ces eaux sont polluées et vivement déconseillées à la consommation humaine. Sur la base des données ponctuelles issues des simulations et des différentes analyses des eaux et des sols, la dynamique de contamination des nappes d’eau superficielles et souterraines dans les zones cristallines fracturées et densément peuplées a été posée. Deux zones de protection ayant respectivement des rayons de 10 mètres et de 20 mètres peuvent être envisagées afin de permettre au sol de jouer pleinement son rôle épurateur. Des mesures adéquates (campagnes d’information, établissement des zones de protection, ...) doivent être engagées dans ce bassin versant et au-delà dans toute la ville de Yaoundé afin de faire face à la dégradation assez avancée des ressources en eau et ceci malgré des contraintes socio-économiques et foncières qui constituent des freins à cette dynamique. [less ▲]

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See detailHydroélectricité et poissons
Ovidio, Michaël ULg; Florence, Hauregard

Learning material (2009)

Chercheur au Laboratoire de Démographie des Poissons et d’Hydroécologie de l’Université de Liège, Michaël OVIDIO présentait le 30 avril dernier, dans le cadre des Jeudis de l’Aquapôle, un exposé sur l’ « ... [more ▼]

Chercheur au Laboratoire de Démographie des Poissons et d’Hydroécologie de l’Université de Liège, Michaël OVIDIO présentait le 30 avril dernier, dans le cadre des Jeudis de l’Aquapôle, un exposé sur l’ « Impact des barrages et des turbinages hydroélectriques sur la dynamique des populations de poissons et la qualité de leurs habitats » . Sans vouloir être source de conflits avec les producteurs d’hydroélectricité, cet exposé avait pour objectif d’informer le grand public sur cette problématique, car la notion d’énergie verte, largement utilisée pour caractériser l’hydroélectricité, ne doit pas s’arrêter au seul aspect des pollutions. [less ▲]

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See detailUn hydrogel de chitosan d’origine non-animale restaure la fonction rhéologique du fluide synovial arthrosique : étude ex vivo
Henrotin, Yves ULg; Rocasalbas, Guillem; Chausson, Mickaël et al

Poster (2016, December)

Detailed reference viewed: 32 (1 ULg)