scholarly journals Numerical and experimental investigation of leaks in viscoelastic pressurized pipe flow

2013 ◽  
Vol 6 (1) ◽  
pp. 11-16 ◽  
Author(s):  
S. Meniconi ◽  
B. Brunone ◽  
M. Ferrante ◽  
C. Massari
Keyword(s):  
Experimental Investigation ◽  
Cross Section ◽  
Pipe Flow ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
External Flow ◽  
Constant Diameter ◽  
Diameter Pipe ◽  
In Series ◽  
The University

Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-line valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

scholarly journals Numerical and experimental investigation of leaks in viscoelastic pressurized pipes

2012 ◽  
Vol 5 (1) ◽  
pp. 473-494
Author(s):  
S. Meniconi ◽  
B. Brunone ◽  
M. Ferrante ◽  
C. Massari
Keyword(s):  
Experimental Investigation ◽  
Cross Section ◽  
Numerical Experiments ◽  
Laboratory Tests ◽  
Numerical Models ◽  
External Flow ◽  
Constant Diameter ◽  
Diameter Pipe ◽  
In Series ◽  
The University

Abstract. This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-line valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). The analysis is based on laboratory tests carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and numerical experiments by means of different 1-D numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the transients, also in the case of a damaged pipes.

Unsteady Flow and Saline Intrusion in Long Sea Outfalls

1992 ◽  
Vol 25 (9) ◽  
pp. 225-234 ◽  
Author(s):  
T. Larsen ◽  
R. Burrows ◽  
L. Engedahl
Keyword(s):  
Numerical Modelling ◽  
Unsteady Flow ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Saline Intrusion ◽  
Pump Operation ◽  
Operation Results ◽  
The University ◽  
Wave Induced ◽  
Sea Outfalls

The internal hydraulics of the multiport diffuser section in long sea outfalls has been studied by laboratory experiments and numerical modelling. The study has run for five years as a coordinated effort at both the University of Liverpool and the University of Aalborg. The investigations have covered such phenomena as saline intrusion, wave influence and unsteady flow caused by pump operation. Results show that numerous flow regimes exist depending on the boundary conditions. Numerical models have been developed to simulate the flow field in the diffuser section and some of the most interesting phenomena, in particular the wave induced saline intrusion, can now be modelled satisfactorily. Some aspects of the behaviour relating to very low fresh water discharges, e.g. unsteady flow when saline wedges are present, are still not very well described.

scholarly journals MODELLING WAVE OVERTOPPING FOR GRASS COVERS AND TRANSITIONS IN DIKE REVETMENTS

2018 ◽  
pp. 53
Author(s):  
Jord J. Warmink ◽  
Vera M. Van Bergeijk ◽  
Weiqui Chen ◽  
Marcel R. A. Van Gent ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Laboratory Experiments ◽  
Numerical Models ◽  
Maximum Flow ◽  
Grass Cover ◽  
Erosion Model ◽  
Wave Overtopping ◽  
The University ◽  
Future Work ◽  
Maximum Flow Velocity ◽  
Future Plans

Transitions in the dike revetment or in the grass cover can significantly affect the wave overtopping discharge and the dike cover erosion. At the University of Twente, two PhD students recently started on the challenge of quantifying the effect of (1) waterside transition on the wave overtopping discharge and (2) transitions in grass covered dikes on dike erosion. In this paper we present their preliminary results and outline their future plans. Firstly, new laboratory experiments show that the existing wave overtopping formulas are not able to accurately predict the overtopping discharge in case of transitions on the waterside slope. Secondly, the analytical dike cover erosion model shows that transitions in grass covers significantly affect the location of maximum flow velocity and potential dike cover erosion. In future work, detailed numerical models will be developed for both the waterside slope and the landward slope to further increase our understanding of the effects of transitions on the wave overtopping discharge and the dike cover erosion.

Strenæ Natalitiæ

2018 ◽  
Author(s):  
William Gibson
Keyword(s):  
Cross Section ◽  
University Of Oxford ◽  
Vice Chancellor ◽  
The University

This chapter looks at Strenæ Natalitiæ, a volume of poems produced by the University of Oxford to celebrate the events of the birth of the Prince of Wales in 1688. The University of Oxford's Strenæ Natalitiæ was a volume of over a hundred poems, with an obligatory introductory poem contributed by vice-chancellor Gilbert Ironside. The contibutors to Strenæ Natalitiæ were not simply a cross-section of the university's membership and poetic talent, but also of its politics. In some respects, youthful naivety might have been a cause of some of the authors' willingness to embrace the birth of James Edward, despite the anxiety felt by some of their fellow authors. Some of the verse was simple, and naïve in tone. Other verses were marked by a more mystical and prophetic tone. Ultimately, the verses in Strenæ Natalitiæ were predictable in their expressions of congratulation and celebration, though some also contained carefully muted expressions of equivocation.

scholarly journals Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Gianluca Zitti ◽  
Nico Novelli ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Offshore Structures ◽  
Fish Farm ◽  
Maximum Displacement ◽  
Drag Forces ◽  
Real Size ◽  
Lift And Drag ◽  
Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

Plane turbulent jets in a bounded fluid layer

1992 ◽  
Vol 241 ◽  
pp. 587-614 ◽  
Author(s):  
T. Dracos ◽  
M. Giger ◽  
G. H. Jirka
Keyword(s):  
Experimental Investigation ◽  
Cross Section ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Two Dimensional ◽  
Vortical Structures ◽  
Secondary Currents ◽  
Fluid Layers ◽  
Bounding Surfaces

An experimental investigation of plane turbulent jets in bounded fluid layers is presented. The development of the jet is regular up to a distance from the orifice of approximately twice the depth of the fluid layer. From there on to a distance of about ten times the depth, the flow is dominated by secondary currents. The velocity distribution over a cross-section of the jet becomes three-dimensional and the jet undergoes a constriction in the midplane and a widening near the bounding surfaces. Beyond a distance of approximately ten times the depth of the bounded fluid layer the secondary currents disappear and the jet starts to meander around its centreplane. Large vortical structures develop with axes perpendicular to the bounding surfaces of the fluid layer. With increasing distance the size of these structures increases by pairing. These features of the jet are associated with the development of quasi two-dimensional turbulence. It is shown that the secondary currents and the meandering do not significantly affect the spreading of the jet. The quasi-two-dimensional turbulence, however, developing in the meandering jet, significantly influences the mixing of entrained fluid.

Turbulent buoyant convection from a source in a confined region

1969 ◽  
Vol 37 (1) ◽  
pp. 51-80 ◽  
Author(s):  
W. D. Baines ◽  
J. S. Turner
Keyword(s):  
Point Source ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Region Of Interest ◽  
Constant Cross Section ◽  
General Shape ◽  
Turbulent Environment ◽  
Starting Conditions ◽  
Upward Velocity ◽  
Local Mean

This paper considers the effect of continuous convection from small sources of buoyancy on the properties of the environment when the region of interest is bounded. The main assumptions are that the entrainment into the turbulent buoyant region is at a rate proportional to the local mean upward velocity, and that the buoyant elements spread out at the top of the region and become part of the non-turbulent environment at that level. Asymptotic solutions, valid at large times, are obtained for the cases of plumes from point and line sources and also periodically released thermals. These all have the properties that the environment is stably stratified, with the density profile fixed in shape, changing at a uniform rate in time at all levels, and everywhere descending (with ascending buoyant elements).The analysis is carried out in detail for the point source in an environment of constant cross-section. Laboratory experiments have been conducted for this case, and these verify the major predictions of the theory. It is then shown how the method can be extended to include more realistic starting conditions for the convection, and a general shape of bounded environment. Finally, the model is applied quantitatively to a variety of problems in engineering, the atmosphere and the ocean, and the limitations on its use are discussed.

Numerical and experimental investigation of transient pipe flow

1994 ◽  
Vol 32 (5) ◽  
pp. 689-706 ◽  
Author(s):  
Amgad S. Elansary ◽  
M. Hanif Chaudhry ◽  
Walter Silva
Keyword(s):  
Experimental Investigation ◽  
Pipe Flow ◽  
Transient Pipe Flow
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