Flow observations and mass transfer characteristics in symmetrical wavy-walled channels at moderate Reynolds numbers for steady flow

Nishimura, Tatsuo; Murakami, Shinichiro; Arakawa, Shingho; Kawamura, Yoshiharu

doi:10.1016/0017-9310(90)90067-5

Cited by 117 publications

(5 citation statements)

References 19 publications

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“…Nishimura found that laminar turbulent transition occurred when Re was between 200 and 350, which was far less than the critical Reynold's number of the conventional straight path. 12,13 Other similar experimental results were also reported at a number of times. 14 There are two reasons for this: first, because of the small cross-sectional area of the flow passage which can be easily affected by the roughness of the wall and so on; second, because of the labyrinth's complicated flow channel boundaries, the structures are bending and changeable which is more likely to turn laminar flow to turbulent flow as shown in equation (1) 15…”

Section: Mathematical Model and Simulation Methodssupporting

confidence: 77%

The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment

Long

et al. 2018

Advances in Mechanical Engineering

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Small but complicated labyrinth channel emitters are easily clogged. In this study, computational fluid dynamics-discrete element method coupling approach was employed to investigate the mechanism of emitter clogging caused by particles in size of 65, 100, and 150 mm. Computational fluid dynamics used Navier-Stokes equation to analyze flow characteristics of continuous phase. Discrete element method used Newton's laws of motion to measure single particle motion and group distribution of disperse phase. Particle tracking velocimetry was also utilized to follow the trajectories and velocity of single particle. Our results indicated that the smaller the particle size, the less the total force. Tiny sands were mainly influenced by drag forces. The amplitude between tooth tips was small. Particles moved basically in the main stream with fast velocity and short travel distance, thereby having good following performance. It took shorter time to reach microdynamic balance. Meanwhile, the amount of sediments in the labyrinth channel was less. Particles in size of 150 mm were mainly affected by inertial forces. They can easily enter vortex areas. Sands staying longer than 0.1 s in the labyrinth channel accounted for 37.9% of total number. Sand groups were mainly distributed at the inlet of labyrinth channel. The more sands trapped in vortex areas, the easier it was to precipitate and cause emitter clogging.

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Section: Mathematical Model and Simulation Methodssupporting

confidence: 77%

The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment

Long

et al. 2018

Advances in Mechanical Engineering

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“…However, there are large number of numerical models and experimental studies that offer qualitative data (Gschwind et al, 1995). used a meandering amplitude of the same order of magnitude as the channel height, and (Nishimura et al, 1990;Tatsuo et al, 1990) used a large amplitude compared to the channel height to demonstrate the existence of streamwise vortices attributed to the centrifugal instability in sinusoidal channels. Rush et al (Rush et al, 1999) has qualitatively identified the additional types of instability for corresponding geometries.…”

Section: Introductionmentioning

confidence: 99%

Investigation of fluid flow pattern in a 3D meandering tube

Ibrahim¹,

Marwat²,

Ullah³

et al. 2023

Front. Mater.

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Several types of meandering channels and their mathematical simulation have been proposed and discussed widely in the open literature. In the present study, the impact of a novel meandering tube geometry on streamwise vortices and pressure losses have been determined. Using a simplified Poiseuille flow simulation approach with a sinusoidal wavy meandering tube of non-uniform radius, the onset flow separation, vertex formation, and the impact of Reynolds number on field variables and stream function has been analyzed. Moreover, the linear stability theory has been implemented to trace the vertex formation. A decrease in wavelength leads to flow separation near the tube’s surface, but the flow becomes rectilinear with a sudden disturbance caused by the meander, becoming independent of vertex generating centrifugal forces. Novel insights are provided on the impact of meandering tube geometry on fluid flow and potential applications for enhancing flow conditions are suggested.

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“…At higher values of Re, the rate of heat transfer was observed to be significant at a larger value of amplitude wavelength ratio. Nishimura et al [4] performed an experimental investigation of the heat transfer for a laminar flow inside a symmetric 2D wavy channel. Two different geometries of the channel wall namely, sinusoidal wall and arc-shaped wall were investigated to study the flow and heat transfer behaviours for Re = 20 to 300.…”

Section: -Introductionmentioning

confidence: 99%

Effect of rotation on forced convection in wavy wall channels

Al-Zurfi

Alhusseny

Nasser

2020

International Journal of Heat and Mass Transfer

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In this paper, flow field and heat transfer performance in stationary and rotating wavy channels with different shapes were numerically investigated. Three different geometries were generated through three different values of phase-shift angles of = 0, 90 and 180 degrees between ∅ the two opposite wavy walls. A cell-centred finite-volume technique was employed to solve the three-dimensional governing equations based on the SIMPLE algorithm technique. Besides, the Menter k-SST turbulence model was used to simulate the turbulent flow in the current study. The wavelength and wave amplitude of the channel examined were L w =20 mm and a=2 mm, respectively. Numerical simulations were carried out over a range of design and operating conditions including the phase-shift angle of = 0-180 degrees, Reynolds number of Re=1,000-∅ 10,000, and rotating speed of 0-1000 rpm. The results showed that the surface-averaged Ω = Nusselt number increases as Re increases for all shapes of the wavy channel, however, at the expense of the raised pressure losses. Also, the wavy channel with a phase-shift of = 0 deg ∅ showed the highest enhancement in the performance of heat transfer followed by that of 90 ∅ = and 180 deg, respectively. The rotation had a strong impact on the flow field and heat transfer performance. With the increase of rotating speed, lower wall heat transfer coefficient significantly increased, while the upper wall heat transfer coefficient exhibited a slight increase, indicating that those three different geometries of the wavy channels had a good versatility at various values of rotating speeds. The numerical results were compared with those available in the literature, and the results were in a good agreement.

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Flow observations and mass transfer characteristics in symmetrical wavy-walled channels at moderate Reynolds numbers for steady flow

Cited by 117 publications

References 19 publications

The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment

The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment

Investigation of fluid flow pattern in a 3D meandering tube

Effect of rotation on forced convection in wavy wall channels

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