Stability and existence of multiple solutions for viscous flow in suddenly enlarged channels

Shapira, Moshe; Degani, David; Weihs, D.

doi:10.1016/0045-7930(90)90009-m

Cited by 107 publications

(89 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Essentiellement, pour décrire l'évolution spatiale et temporelle des perturbations. ils ont montré que la stabilité linéaire présente les effets de la viscosité de l'eau et du frottement du fond Chen et Jirka, [1998], Shipara et al, [1990]. Cependant, par expérimentation et modélisation numérique Mizushima et Shiotani, [1996-2001 ont examiné l'effet de l'allongement du bassin sur la stabilité linéaire des écoulements dans les canaux avec élargissement brusque.…”

Section: Introductionunclassified

Effet de la rugosité du fond d'un réservoir rectangulaire à faible profondeur sur le champ d'écoulement

2014

View full text Add to dashboard Cite

RÉSUMÉ. -La sédimentation de la charge en suspension dans les réservoirs est un phénomène assez complexe à gérer. Des solutions existent pour maitriser ou réduire l'alluvionnement mais elles ne sont généralement pas faciles à expliquer, surtout dans les retenues traversées par l'écoulement. Dans ce contexte, une étude expérimentale a été réalisée dans le but d'examiner l'effet de la rugosité du fond du réservoir peu profond sur le mode d'écoulement. Les essais ont été effectués dans un bassin de largeur B = 4 m, de longueur L = 6 m et de profondeur h = 0.2 m. Les profils des vitesses longitudinales ont été mesurés par des capteurs UVP (Ultrasonic Velocimetry Profiler). Une mesure par Large Scale Particle Image Velocimetry LSPIV a été également utilisée pour définir les champs de vitesses en surface par interpréta-tion d'images vidéo zénithales. Sur fond lisse, les écoulements dans le réservoir se développent de manière asymétrique en dépit des conditions géométriques initialement symétriques. Avec l'ajout d'une rugosité au fond du bassin, les conditions d'écoulement se stabilisent et présentent un champ de vitesses symétrique. Les résultats obtenus ont montré que le régime d'écoulement est très sensible aux conditions de bords qui influencent significativement le champ des vitesses de surface dans un réservoir peu profond. L'augmentation de la rugosité du lit accroit le frottement et l'épaisseur de la couche limite, avec pour conséquence de rétablir la symétrie d'écoulement. Mots-clés : réservoir peu profond, rugosité du fond, UVP, LSPIV, champ d'écoulement. Bed roughness effect on flow field in rectangular shallow reservoirABSTRACT. -The sedimentation by suspended sediments in the reservoir is a complex phenomenon operates. Actually, some solutions exist to control or to reduce reservoir sedimentation but, generally, they are not very easy to implement especially in reservoir crossed by the flow. In this context, an experimental study was studied in order to examine the bottom roughness effect in a shallow reservoir. The tests were carried out in rectangular reservoir of width B = 4 m, length L = 6 m and depth h = 0.2 m. The velocity profiles were measured by UVP (Ultrasonic Velocity Profiler). LSPIV (Large Scale Particle Image Velocimetry) was also used to define the field velocity on the surface by interpretating of zenith video images. On the smooth bottom, asymmetrical flow is developed in the reservoir in spite of boundary conditions and geometrical perfectly symmetrical. With the addition a roughness surface at the bottom of reservoir; conditions flow are stabilized and presented a symmetrical recirculating. Experiment has showed the flow is very sensitive to geometrical conditions which significantly influence the velocity field in the basin. The increase in bottom roughness, the friction forces and turbulent thickness of boundary conditions layer with for consequence restoring in the symmetric flow.

show abstract

Section: Introductionunclassified

Effet de la rugosité du fond d'un réservoir rectangulaire à faible profondeur sur le champ d'écoulement

2014

View full text Add to dashboard Cite

show abstract

“…These configurations are included in the instability zone of transition between the symmetric flow-field region and the asymmetric flow-field region, which is defined by the two critical values of the non-dimensional shape parameter T 4.09 and T = 4.48, as proposed by Dufresne et at. (Shapira et al 1990): two solutions of the Navier-Stokes equations exist, one corresponding to the symmetric, the other to the asymmetric flow field. Outside this instability region the flow pattern is stable, in the sense that the type of flow field is not sensitive to external disturbances.…”

Section: Ch-l°°4mentioning

confidence: 99%

Experimental study of velocity fields in rectangular shallow reservoirs

Camnasio

Orsi

Schleiss

2011

Journal of Hydraulic Research

View full text Add to dashboard Cite

Velocity fields in rectangular shallow reservoirs with different length-to-width and expansion ratios were investigated in an experimental study, to ate the effect of geometry on the flow field. A wide range of combinations of these two non-dimensional geometric parameters were tested at hydraulic conditions. Ultrasound velocity profilers were used to measure the horizontal velocity components across the entire reservoir surface, ing for the visualization of streamlines and of the instantaneous and average velocities. Five different types of flow patterns were identified, de!)endiI1lg on the values of the length-to-width ratio and expansion ratio of the reservoir. Asymmetrical flow patterns were found to develop for certain nations of these geometric parameters despite the perfect reservoir symmetry. A critical comparison of these new experimental results with those other works is provided.c"f

show abstract

“…Flow pattern in wide and shallow reservoirs with sudden expansion of inlet section may become unstable, which produces large-scale transverse motions and recirculation zones due to the transverse disturbance because of the high sensitivity of flow pattern to the initial and boundary condition (Dewals et al 2008). This type of flows is prominent in the nature and also emerges in various engineering applications including sudden expansions (Shapira et al 1990), compound channels (Ghidaoui &Kolyshkin 1999 andChu et al 1991), storage chambers (Adamson et al 2003), settling tanks (Frey et al 1993) as well as shallow reservoirs sedimentation (Kantoush et al 2008a(Kantoush et al & 2010.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional numerical modeling of flow field in rectangular shallow reservoirs

Esmaeili¹,

Sumi²,

Schleiss³

et al. 2014

Reservoir Sedimentation

View full text Add to dashboard Cite

Flow field in shallow waters, which is characterized by its complex mixing process and inherent dynamic nature, is interesting mainly due to its practical importance (e. g. in free flushing operation and sedimentation in large reservoirs). 3D numerical models make it possible to track two-dimensional large turbulence coherent structures, which are the dominant phenomenon in shallow reservoirs flow field. In the present study a fully three-dimensional numerical model SSIIM that employs the Finite Volume Approach (FVM) was utilized to reproduce the 3D flow field. Various shallow reservoir geometries with fixed and deformed equilibrium bed were considered. The measurements by Large-Scale Particle Image Velocimetry techniques (LSPIV) and Ultrasonic Doppler Velocity Profiler (UVP) over the flow depth were used for model validation. Outcomes revealed reasonable agreement between the simulated and measured flow velocity field even when an asymmetric flow pattern exists in the reservoir.

show abstract

Stability and existence of multiple solutions for viscous flow in suddenly enlarged channels

Cited by 107 publications

References 7 publications

Effet de la rugosité du fond d'un réservoir rectangulaire à faible profondeur sur le champ d'écoulement

Effet de la rugosité du fond d'un réservoir rectangulaire à faible profondeur sur le champ d'écoulement

Experimental study of velocity fields in rectangular shallow reservoirs

Three-dimensional numerical modeling of flow field in rectangular shallow reservoirs

Contact Info

Product

Resources

About