scholarly journals Bed-Shear Velocity Measurement in Curved Open Channel

2021 ◽  
Vol 004 (01) ◽  
pp. 093-105
Author(s):  
Sumiadi Sumiadi ◽  
Bambang Kironoto ◽  
Djoko Legono ◽  
Istiarto Istiarto
Keyword(s):  
Stress Distribution ◽  
Reynolds Stress ◽  
Measurement Data ◽  
Shear Velocity ◽  
Complex Flow ◽  
Curved Channel ◽  
Distribution Method ◽  
Bed Topography ◽  
Curved Channels ◽  
River Bed

Generally, the condition of the rivers in Indonesia are alluvial rivers which had meanders, where the change in the river bed topography often occur. One of the parameters associated with changes in the river bed topography is bed-shear velocity, or Reynolds stress. The bed-shear velocity can be calculated by the Reynolds stress distribution method and the Clauser method which commonly used in straight channels. In fact, on natural channel there is a curve and even a meandering channel. With more complex flow conditions, the use of the Clauser method in curved channels can be questioned, is it still accurate or not. In this paper, both methods will be discussed by comparing the measurement data in the laboratory using 180 curved channel with flat bed. The results of data analysis show that the use of these two methods in curved channels produces an average difference of around 19.81%, where the Clauser method gives greater results and better tendencies. Apart from the differences in the results given, it can be said that the Clauser method as well as the Reynolds stress distribution method can still be used to calculate the bed-shear velocity in the curved channel

Development of a Two-Dimensional Turbulent Wake in a Curved Channel With a Positive Streamwise Pressure Gradient

1996 ◽  
Vol 118 (2) ◽  
pp. 292-299 ◽  
Author(s):  
J. John ◽  
M. T. Schobeiri
Keyword(s):  
Pressure Gradient ◽  
Reynolds Stress ◽  
Gaussian Function ◽  
Two Dimensional ◽  
Curved Channel ◽  
Mean Velocity ◽  
Velocity Defect ◽  
Curved Channels ◽  
Stress Components ◽  
Streamwise Pressure Gradient

The development of turbomachinery wake flows is greatly influenced by streamline curvature and streamwise pressure gradient. This paper is part of a comprehensive experimental and theoretical study on the development of the steady and periodic unsteady turbulent wakes in curved channels at different streamwise pressure gradients. This paper reports on the experimental investigation of the two-dimensional wake behind a stationary circular cylinder in a curved channel at positive streamwise pressure gradient. Measurements of mean velocity and Reynolds stress components are carried out using a X-hot-film probe. The measured quantities obtained in probe coordinates are transformed to a curvilinear coordinate system along the wake center line and are presented in similarity coordinates. The results show strong asymmetry in velocity and Reynolds stress components. The Reynolds stress components have higher values at the inner half of the wake than at the outer half of the wake. However, the mean velocity defect profiles in similarity coordinates are almost symmetric and follow the same Gaussian function for the straight wake data. A comparison with the wake development in a curved channel at zero streamwise pressure gradient suggests the decay rate of velocity defect is slower and the growth of wake width is faster for a positive streamwise pressure gradient.

scholarly journals Development of Periodic Unsteady Turbulent Wakes in a Curved Channel at Zero Streamwise Pressure Gradient

1994 ◽  
Author(s):  
M. T. Schobeiri ◽  
J. John
Keyword(s):  
Pressure Gradient ◽  
Coordinate System ◽  
Reynolds Stress ◽  
Temporal Distribution ◽  
Curved Channel ◽  
Spatial Coordinate ◽  
Curved Channels ◽  
Turbulent Wakes ◽  
Streamwise Pressure Gradient ◽  
Hot Film

The development of turbomachinery wake flows is influenced by streamline curvature and streamwise pressure gradient. This paper is a part of a comprehensive experimental and analytical study on the development of the steady and periodic unsteady turbulent wakes in curved channels at different longitudinal (streamwise) pressure gradients. The development of periodic unsteady wakes in a curved channel at zero longitudinal pressure gradient is reported in this paper. Instantaneous velocity components of the periodic wakes, measured using a X-hot-film probe, are analyzed by employing phase-averaging techniques. The temporal distribution of phase-averaged velocity and Reynolds stress components obtained in stationary frame of reference are transformed to a relative spatial coordinate system. The profiles of the velocity and Reynolds stress distribution in relative spatial coordinate system and similarity coordinates are consistent with the measurements of the wake development behind stationary cylinder in the same curved channel.

EFEECTS OF WEIR WITH AN OPENING ON RIVER BED TOPOGRAPHY

2020 ◽  
Vol 76 (2) ◽  
pp. I_1195-I_1200
Author(s):  
Hirotaka UNE ◽  
Terunori OHMOTO ◽  
Kazuki KURANAGA
Keyword(s):  
Bed Topography ◽  
River Bed

scholarly journals Numerical Study of Paramagnetic Elliptical Microparticles in Curved Channels and Uniform Magnetic Fields

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Christopher Sobecki ◽  
Jie Zhang ◽  
Cheng Wang
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Spherical Particles ◽  
Biological Applications ◽  
Arbitrary Lagrangian Eulerian ◽  
Curved Channel ◽  
Radial Migration ◽  
Wall Distance ◽  
Curved Channels ◽  
The Magnetic Field

We numerically investigated the dynamics of a paramagnetic elliptical particle immersed in a low Reynolds number Poiseuille flow in a curved channel and under a uniform magnetic field by direct numerical simulation. A finite element method, based on an arbitrary Lagrangian-Eulerian approach, analyzed how the channel geometry, the strength and direction of the magnetic field, and the particle shape affected the rotation and radial migration of the particle. The net radial migration of the particle was analyzed after executing a π rotation and at the exit of the curved channel with and without a magnetic field. In the absence of a magnetic field, the rotation is symmetric, but the particle-wall distance remains the same. When a magnetic field is applied, the rotation of symmetry is broken, and the particle-wall distance increases as the magnetic field strength increases. The causation of the radial migration is due to the magnetic angular velocity caused by the magnetic torque that constantly changes directions during particle transportation. This research provides a method of magnetically manipulating non-spherical particles on lab-on-a-chip devices for industrial and biological applications.

Turbulent Flow of Water in Plane Curved Channels of Finite Depth

1963 ◽  
Vol 85 (3) ◽  
pp. 377-390 ◽  
Author(s):  
O. G. Brown ◽  
A. W. Marris
Keyword(s):  
Experimental Study ◽  
Shear Flow ◽  
Turbulent Flow ◽  
Finite Depth ◽  
Width Ratio ◽  
Mean Flow ◽  
Curved Channel ◽  
Flow Acceleration ◽  
Curved Channels ◽  
Convex Wall

An experimental study of turbulent flow in a plane curved channel of depth-to-width ratio 8:1 and mean radius-to-width ratio 1.83:1 by means of measured distributions of mean peripheral velocity and pressure and flow visualization methods using dye. It appears that due to the large depth-to-width ratio, the secondary flow, though appreciable, is apparent mainly in the end plate regions. Even so it has a pronounced effect on the flow near the inner (convex) wall. It appears that the sharp curvature is effective in quenching the turbulence of the entering rectilinear shear flow at the inner wall of the curved channel by causing a mean flow acceleration in this region. The study indicates that localized backflows can occur at the inner wall at the meeting of secondary and main flows under near-laminar conditions.

scholarly journals Motion of large bubbles in curved channels

2007 ◽  
Vol 570 ◽  
pp. 455-466 ◽  
Author(s):  
METIN MURADOGLU ◽  
HOWARD A. STONE
Keyword(s):  
Film Thickness ◽  
Liquid Velocity ◽  
Circular Cross Section ◽  
Lubrication Theory ◽  
Bubble Velocity ◽  
Straight Tube ◽  
Curved Channel ◽  
Front Tracking Method ◽  
Curved Channels ◽  
Channel Curvature

We study the motion of large bubbles in curved channels both semi-analytically using the lubrication approximation and computationally using a finite-volume/front-tracking method. The steady film thickness is governed by the classical Landau–Levich–Derjaguin–Bretherton (LLDB) equation in the low-capillary-number limit but with the boundary conditions modified to account for the channel curvature. The lubrication results show that the film is thinner on the inside of a bend than on the outside of a bend. They also indicate that the bubble velocity relative to the average liquid velocity is always larger in a curved channel than that in a corresponding straight channel and increases monotonically with increasing channel curvature. Numerical computations are performed for two-dimensional cases and the computational results are found to be in a good agreement with the lubrication theory for small capillary numbers and small or moderate channel curvatures. For moderate capillary numbers the numerical results for the film thickness, when rescaled to account for channel curvature as suggested in the lubrication calculation, essentially collapse onto the corresponding results for a bubble in a straight tube. The lubrication theory is also extended to the motion of large bubbles in a curved channel of circular cross-section.

scholarly journals Investigation of Shear Stress Distribution in a 90 Degree Channel Bend

2019 ◽  
Vol 24 (1) ◽  
pp. 213-220
Author(s):  
Seung Kyu Lee ◽  
Truong An Dang ◽  
Van Tuan Le
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
River Flow ◽  
Morphological Changes ◽  
Measurement Data ◽  
Shear Stress Distribution ◽  
Doppler Velocity ◽  
Channel Bend ◽  
Outer Bank ◽  
Maximum Value

Abstract Shear stress is a key parameter that plays an important role in sediment transport mechanisms; therefore, understanding shear stress distribution in rivers, and especially in river bends, is necessary to predict erosion, deposition mechanisms and lateral channel migration. The aim of this study is to analyze the shear stress distribution near a river bed at 90-degree channel bend using a depth-average method based on experimental measurement data. Bed shear stress distribution is calculated using the depth-averaged method based on velocity components data has been collected from a 3D-ADV device (three-dimensional acoustic doppler velocity) at different locations of a meandering channel. Laboratory experiments have been made at the hydraulic laboratory of the RCRFIDF (Research Center for River Flow Impingement and Debris Flow), Gangneung-Wonju National University, South Korea to provide data for simulating the incipient motion of the riverbed materials and then predicting the river morphological changes in the curved rivers. The calculated results show that the maximum value of shear stress distribution near the riverbed in the different cross sections of the surveyed channel occurs in a 70-degree cross section and occurs near the outer bank. From the beginning of a 40-degree curved channel section, the maximum value of the shear stress occurs near the outer bank at the end of the channel.

scholarly journals Construction of N-M Interaction Diagram for Reinforced Concrete Columns Strengthened with Steel Jackets Using Plastic Stress Distribution Method

2017 ◽  
Vol 3 (10) ◽  
pp. 929
Author(s):  
Mohannad Husain Al-Sherrawi ◽  
Hamza M. Salman
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Stress Distribution ◽  
Concrete Columns ◽  
Concrete Compressive Strength ◽  
Distribution Method ◽  
Reinforced Concrete Columns ◽  
Interaction Diagram ◽  
Steel Angle ◽  
Plastic Stress

No attempts have been made in developing the N-M interaction diagram for reinforced concrete columns strengthened with steel jackets using the plastic stress distribution method. Therefore, this paper presents an analytical model to construct the N-M interaction diagram for reinforced concrete columns strengthened with steel jackets using the plastic stress distribution method after assuming the behavior of strengthened column to be like composite column and including the effects of confinement on concrete compressive strength. The proposed model was compared with experimental results. The comparisons showed that the model is conservative and it reveals the ultimate strength of the strengthened column. A parametric study has been also carried out to investigate the influence of various parameters on the N-M interaction diagram of the strengthened column. These parameters were: dimensions of steel angle, yield stress of the steel angles, concrete compressive strength and the size of the reinforcement bars used in RC columns. The results made clear the effects of these parameters on the N-M interaction diagram, and encouraged the use of the model in preliminary strengthening studies.

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