Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailHydrodynamic forces acting on vertically translating bodies in free surface water
Kerger, François ULg; Detrembleur, Sylvain ULg; Archambeau, Pierre ULg et al

in WIT Transactions on The Built Environment, Vol 105, Fluid Structure Interaction V (2009, May)

Detailed reference viewed: 48 (12 ULg)
Full Text
Peer Reviewed
See detailHydrodynamic instabilities in shallow reservoirs: implications for sediment management
Peltier, Yann; de Cuyper, Anaïs; Erpicum, Sébastien ULg et al

Conference (2016)

Detailed reference viewed: 31 (4 ULg)
See detailHydrodynamic modelling, damage evaluation and technical adaptation measures
Dewals, Benjamin ULg

Conference (2008, January 10)

Detailed reference viewed: 6 (2 ULg)
Peer Reviewed
See detailHydrodynamic models of the West European Shelf
Djenidi, Salim ULg; Nihoul, Jacques ULg; Ronday, François ULg

in Phys. of Shallow Bays, Estuaries and Cont. Shelves (1986)

Detailed reference viewed: 7 (3 ULg)
Full Text
See detailHydrodynamic simulations of galaxy formation
Thoul, Anne ULg

in Dark Matter (1995, July)

We have developed an accurate, one-dimensional, spherically symmetric, Lagrangian hydrodynamics/gravity code, designed to study the effects of radiative cooling and photo-ionization on the formation of ... [more ▼]

We have developed an accurate, one-dimensional, spherically symmetric, Lagrangian hydrodynamics/gravity code, designed to study the effects of radiative cooling and photo-ionization on the formation of protogalaxies. We examine the ability of collapsing perturbations to cool within the age of the universe. In contrast to some studies based on order-of-magnitude estimates, we find that cooling arguments alone cannot explain the sharp upper cutoff observed in the galaxy luminosity function. We also look at the effect of a photoionizing background on the formation of low-mass galaxies. [less ▲]

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailHYDRODYNAMIC SIMULATIONS OF GALAXY FORMATION .1. DISSIPATION AND THE MAXIMUM MASS OF GALAXIES
Thoul, Anne ULg; WEINBERG, D. H.

in Astrophysical Journal (1995), 442(2), 480-491

We describe an accurate, one-dimensional, spherically symmetric Lagrangian hydrodynamics/gravity code, designed to study the effects of radiative cooling and photoionization on the formation of ... [more ▼]

We describe an accurate, one-dimensional, spherically symmetric Lagrangian hydrodynamics/gravity code, designed to study the effects of radiative cooling and photoionization on the formation of protogalaxies. The code can treat an arbitrary number of fluid shells (representing baryons) and collisionless shells (representing cold dark matter). As a test of the code, we reproduce analytic solutions for the pulsation behavior of a poly-trope and for the self-similar collapse of a spherically symmetric, cosmological perturbation. In this paper we concentrate on the effects of radiative cooling, examining the ability of collapsing perturbations to cool within the age of the universe. In contrast to some studies based on order-of-magnitude estimates, we find that cooling arguments alone cannot explain the sharp upper cutoff observed in the galaxy luminosity function. [less ▲]

Detailed reference viewed: 23 (3 ULg)
Full Text
Peer Reviewed
See detailHydrodynamic simulations of galaxy formation .2. Photoionization and the formation of low-mass galaxies
Thoul, Anne ULg; Weinberg, D. H.

in Astrophysical Journal (1996), 465(2), 608-616

Photoionization by the high-redshift ultraviolet radiation background heats low- density gas before it falls into dark matter potential wells, and it eliminates the neutral hydrogen and singly ionized ... [more ▼]

Photoionization by the high-redshift ultraviolet radiation background heats low- density gas before it falls into dark matter potential wells, and it eliminates the neutral hydrogen and singly ionized helium that dominate cooling of primordial gas at temperatures of 10(4)-10(5) K. We investigate the influence of photoionization on galaxy formation using high-resolution simulations with a one-dimensional, spherically symmetric, Lagrangian hydrodynamics/gravity code. We find that the presence of a photoionizing background suppresses the formation of galaxies with circular velocities v(circ) less than or similar to 30 km s(-1) and substantially reduces the mass of cooled baryons in systems with circular velocities up to v(circ) similar to 50 km s(-1). Above v(circ) similar to 75 km s(-1), photoionization has no significant effect. Photoionization exerts its influence primarily by heating gas before collapse; the elimination of line cooling processes is less important. We discuss the implications of these results for hierarchical theories of galaxy formation. [less ▲]

Detailed reference viewed: 21 (4 ULg)
See detail"Hydrodynamic Stress of Cellulases in a Bioreactor"
Meurisse, E.; Evrard, J. F.; Denoo, O. et al

in Mededelingen - Faculteit Landbouwwetenschappen, Rijksuniversiteit Gent (1993), 58(4b), 1981-1983

Detailed reference viewed: 35 (14 ULg)
See detailHydrodynamic stress of Dunaliella tertiolecta.
Rikir, R.; Spoiden, J. F.; Thonart, Philippe ULg

Poster (1990, July)

Detailed reference viewed: 14 (0 ULg)
Full Text
Peer Reviewed
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)
Peer Reviewed
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)

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
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)

Detailed reference viewed: 1 (1 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 12 (2 ULg)
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 ▲]

Detailed reference viewed: 20 (7 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 76 (20 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 89 (26 ULg)
Full Text
Peer Reviewed
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)

Detailed reference viewed: 10 (1 ULg)
Full Text
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 ▲]

Detailed reference viewed: 53 (5 ULg)