Sedimentation of solid particles in turbulent flow in horizontal channels

2004 ◽  
Vol 140 (1-2) ◽  
pp. 79-85 ◽  
Author(s):  
Ayse Sarimeseli ◽  
Gudret Kelbaliyev
Keyword(s):  
Turbulent Flow ◽  
Solid Particles

scholarly journals SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA

Irriga ◽  
2018 ◽  
Vol 23 (2) ◽  
pp. 194-203
Author(s):  
Acácio Perboni ◽  
José Antonio Frizzone ◽  
Rubens Duarte Coelho ◽  
Rogério Lavanholi ◽  
Ezequiel Saretta
Keyword(s):  
Turbulent Flow ◽  
Flow Rate ◽  
Flow Regimes ◽  
Solid Particles ◽  
Automated System ◽  
Particle Sizes ◽  
Initial Flow ◽  
Water Flow Velocity ◽  
Sand Particles ◽  
Micro Irrigation

SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA     ACÁCIO PERBONI1; JOSÉ ANTONIO FRIZZONE2; RUBENS DUARTE COELHO2; ROGÉRIO LAVANHOLI3 E EZEQUIEL SARETTA4   1 Professor, IFMT, Campo Novo do Parecis - MT, [email protected] 2 Professor, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected]; [email protected] 3 Doutorando, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected] 4 Professor, UFSM, Cachoeira do Sul - RS, [email protected]     1 RESUMO   O objetivo deste trabalho foi avaliar a influência do tamanho e concentração de partículas de areia e da velocidade de fluxo da água nas linhas na sensibilidade à obstrução de um modelo de gotejador do tipo cilíndrico, não regulado, com vazão nominal de 2 L h-1. Foram realizados ensaios de obstrução com areia misturada em água destilada, combinando os seguintes fatores: três faixas granulométricas de partículas de areia, três concentrações de areia e três velocidades de fluxo de água no tubo. A vazão de 32 gotejadores foi medida a cada doze minutos por meio de um sistema automatizado. Nos ensaios com faixa granulométrica de 0,105 a 0,25 mm, ocorreu a obstrução nas concentrações de 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. Já na faixa granulométrica de 0,25 a 0,5 mm, ocorreu obstrução nas concentrações de 100, 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. A obstrução de gotejadores ocorreu de forma aleatória nas oito linhas. Após obstruídos os gotejadores não desobstruíram com o passar do tempo de ensaio.   Palavras-chave: microirrigação, partículas sólidas inertes, granulometria, concentração     PERBONI, A.; FRIZZONE, J. A.; COELHO, R. D.; LAVANHOLI, R.; SARETTA, E. SENSITIVITY OF DRIPPERS TO CLOGGING CAUSED BY SAND PARTICLES     2 ABSTRACT   The purpose of this research was to assess the influence of concentration and size of sand particles, and water flow velocity in laterals on the sensitivity of drippers to clogging. A cylindrical integrated non-pressure compensating dripper of 2 L h-1 nominal flow rate was used. Experiments were undertaken using distilled water and sand particles, according to the following levels: (a) three ranges of particles sizes; (b) three concentrations of particles; and, (c) three flow velocities in the laterals. The flow rate of 32 drippers was measured at every 12 minutes by an automated system. Within the range of particle sizes from 0.105 to 0.25 mm, clogging of emitters was observed under transient and turbulent flow regimes, and under particles concentration of 250 and 500 mg L-1. Within the range of particles sizes from 0.25 to 0.5 mm, clogging was observed for all concentrations under transient and turbulent flow regimes. Clogging of emitters occurred as a random phenomenon. Once clogged, emitters did not recover their initial flow rate.    Keywords: micro irrigation, inert solid particles, particle size, concentration

Modeling of the Size Distribution Resulting from Dissolution of Spherical Solid Particles in Turbulent Flow

2012 ◽  
Vol 33 (4) ◽  
pp. 521-526 ◽  
Author(s):  
Ahmet Ekmekyapar ◽  
Asım Künkül ◽  
Mehmet Yüceer ◽  
Gudret Kelbaliyev
Keyword(s):  
Turbulent Flow ◽  
Size Distribution ◽  
Solid Particles

Direct numerical simulation of turbulent flow and heat transfer in a spatially developing turbulent boundary layer laden with particles

2018 ◽  
Vol 845 ◽  
pp. 417-461 ◽  
Author(s):  
Dong Li ◽  
Kun Luo ◽  
Jianren Fan
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulent Flow ◽  
Solid Particles ◽  
Heated Wall ◽  
Wall Region ◽  
Flow And Heat Transfer ◽  
Particle Laden Flows ◽  
Near Wall

Direct numerical simulations of particle-laden flows in a spatially developing turbulent thermal boundary layer over an isothermally heated wall have been performed with realistic fully developed turbulent inflow boundary conditions. To the authors’ best knowledge, this is the first time the effects of inertial solid particles on turbulent flow and heat transfer in a flat-plate turbulent boundary layer have been investigated, using a two-way coupled Eulerian–Lagrangian method. Results indicate that the presence of particles increases the mean streamwise velocity and temperature gradients of the fluid in the near-wall region. As a result, the skin-friction drag and heat transfer are significantly enhanced in the particle-laden flows with respect to the single-phase flow. The near-wall sweep and ejection motions are suppressed by the particles and hence the Reynolds shear stress and wall-normal turbulent heat flux are attenuated, which leads to reductions in the production of the turbulent kinetic energy and temperature fluctuations. In addition, the coherence and spacing of the near-wall velocity and temperature streaky structures are distinctly increased, while the turbulent vortical structures appear to be disorganized under the effect of the particles. Moreover, the intensity of the streamwise vortices decreases monotonically with increasing particle inertia.

scholarly journals A visual investigation of the wall region in turbulent flow

1969 ◽  
Vol 37 (1) ◽  
pp. 1-30 ◽  
Author(s):  
E. R. Corino ◽  
Robert S. Brodkey
Keyword(s):  
Turbulent Flow ◽  
Transport Processes ◽  
Solid Particles ◽  
Small Scale ◽  
Solid Boundary ◽  
Wall Region ◽  
Mean Flow ◽  
Measuring Device ◽  
Velocity Fluctuations ◽  
The Mean

The objective of this study is to investigate for turbulent flow the fluid motions very near a solid boundary, and to create a physical picture which relates these motions to turbulence generation and transport processes. An experimental technique was developed which permitted detailed observations of the regions very near a pipe wall, including the viscous sublayer, without requiring the introduction of any injection or measuring device into the flow. This technique involved suspending solid particles of colloidal size in a liquid, and photographing their motions with a high-speed motion picture camera moving with the flow. To provide greater detail, the field of view was magnified.Fluid motions were observed to change in character with distance from the wall. The sublayer was continuously disturbed by small-scale velocity fluctuations of low magnitude and periodically disturbed by fluid elements which penetrated into the region from positions further removed from the wall. From a thin region adjacent to the sublayer, fluid elements were periodically ejected outward toward the centreline. Often there was associated with these events a zone of high shear at the interface between the mean flow and the decelerated region that gave rise to the ejected element. When the ejected element entered this shear zone, it interacted with the mean flow and created intense, chaotic velocity fluctuations. These ejections and resulting fluctuations were the most important feature of the wall region, and are believed to be a factor in the generation and maintenance of turbulence.

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