scholarly journals Development of River Meander Model

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Levent Yilmaz
Keyword(s):  
Boundary Layer ◽  
Velocity Profile ◽  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Suspended Sediments ◽  
Flow Region ◽  
Boundary Layer Theory ◽  
Meandering Channels ◽  
Meander Model

In the studies of open-channel flow with suspended sediments, used aconstant of Von Karman κ in a model for velocity profile. The augmentation parameters have been added by various researchers in more recentdevelopment of the boundary-layer theory of meander development. In thisresearch new parameters will be included because of the existence of theturbulent flow region in meandering channels because of boundary-layertheory.

Hydraulics of steeppass fishways

1991 ◽  
Vol 18 (6) ◽  
pp. 1024-1032 ◽  
Author(s):  
N. Rajaratnam ◽  
C. Katopodis
Keyword(s):  
Experimental Study ◽  
Velocity Profile ◽  
Channel Flow ◽  
Flow Rate ◽  
Open Channel ◽  
Maximum Velocity ◽  
Open Channel Flow ◽  
Width Ratio ◽  
Hydraulic Design ◽  
Theoretical Considerations

This paper presents the results of an experimental study on the hydraulics of steeppass fishways. Using theoretical considerations and experimental observations, an expression has been developed that relates the flow rate, slope of the fishway, and depth of flow. It was also found that the characteristic (similarity) velocity profile found earlier, for smaller values of depth to width ratio,y0/b, with the maximum velocity near the bottom, changes to a rather symmetrical profile with the maximum velocity occurring somewhere near the mid-depth for larger values of y0/b. A correlation has also been found for the maximum velocity. This paper also includes some observations on the M-type backwater curves that would appear in the fishway when the tailwater depths exceed uniform flow depths. Key words: fishways, hydraulics, turbulent flow, open-channel flow, hydraulic design.

scholarly journals Flow Partitioning in Rectangular Open Channel Flow

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Yu Han ◽  
Shu-Qing Yang ◽  
Muttucumaru Sivakumar ◽  
Liu-Chao Qiu ◽  
Jian Chen
Keyword(s):  
Shear Stress ◽  
Channel Flow ◽  
Open Channel ◽  
Laser Doppler Anemometry ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Open Channel Flow ◽  
Flow Region ◽  
Mathematical Tool ◽  
Measured Velocity

Hydraulic engineers often divide a flow region into subregions to simplify calculations. However, the implementation of flow divisibility remains an open issue and has not yet been implemented as a fully developed mathematical tool for modeling complex channel flows independently of experimental verification. This paper addresses whether a three-dimensional flow is physically divisible, meaning that division lines with zero Reynolds shear stress exist. An intensive laboratory investigation was conducted to carefully measure the time-averaged velocity in a rectangular open channel flow using a laser Doppler anemometry system. Two innovative methods are employed to determine the locations of division lines based on the measured velocity profile. The results clearly reveal that lines with zero total shear stress are discernible, indicating that the flow is physically divisible. Moreover, the experimental data were employed to test previously proposed methods of calculating division lines, and the results show that Yang and Lim’s method is the most reasonable predictor.

Effect of aspect ratio on developing and developed narrow open channel flow with rough bed

2018 ◽  
Vol 45 (9) ◽  
pp. 780-794 ◽  
Author(s):  
Minakshee Mahananda ◽  
Prashanth Reddy Hanmaiahgari ◽  
Ram Balachandar
Keyword(s):  
Kinetic Energy ◽  
Aspect Ratio ◽  
Channel Flow ◽  
Open Channel ◽  
Reynolds Shear Stress ◽  
Open Channel Flow ◽  
Flow Region ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Rough Bed

This study attempts to unravel the effect of aspect ratio on the turbulence characteristics in developing and fully developed narrow open channel flows. In this regard, experiments were conducted in a rough bed open channel flow. Instantaneous 3D velocities were acquired using an acoustic Doppler velocimeter at various locations along the centerline of the flume. The variables of interest include the mean components of the flow velocity, turbulence intensity, wall normal Reynolds shear stress, correlation coefficient, turbulence kinetic energy, and anisotropy. A new correlation between the equivalent roughness and velocity shift from the smooth wall logarithmic equation as a function of aspect ratio is proposed. Aspect ratio was found to influence the velocity characteristics throughout the depth in the developing flow region, while the effects are confined to the outer layer for fully developed flows. New equations to describe the variation of turbulence intensities and turbulent kinetic energy are proposed for narrow open channel flows. Reynolds stress anisotropy analysis reveals that level of anisotropy in narrow open channel flow is less than in wide open channel flows. Finally, a linear regression model is proposed to predict flow development length in narrow open channel flows with a rough bed.

PIV Study of Separated and Reattached Open Channel Flow Over Surface Mounted Blocks

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Martin Agelinchaab ◽  
Mark F. Tachie
Keyword(s):  
Boundary Layer ◽  
Shear Layer ◽  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Mean Velocity ◽  
High Background ◽  
The Mean

A particle image velocimetry is used to study the mean and turbulent fields of separated and redeveloping flow over square, rectangular, and semicircular blocks fixed to the bottom wall of an open channel. The open channel flow is characterized by high background turbulence level, and the ratio of the upstream boundary layer thickness to block height is considerably higher than in prior experiments. The variation of the Reynolds stresses along the dividing streamlines is discussed within the context of vortex stretching, longitudinal strain rate, and wall damping. It appears that wall damping is a more dominant mechanism in the vicinity of reattachment. In the recirculation and reattachment regions, profiles of the mean velocity, turbulent quantities, and transport terms are used to document the salient features of block geometry on the flow. The flow characteristics in these regions strongly depend on block geometry. Downstream of reattachment, a new shear layer is formed, and the redevelopment of the shear layer toward the upstream open channel boundary layer is studied using the boundary layer parameters and Reynolds stresses. The results show that the mean flow rapidly redeveloped so that the Clauser parameter recovered to its upstream value at 90 step heights downstream of reattachment. However, the rate of development close to reattachment strongly depends on block geometry.

scholarly journals Effects of kinetic sorptive exchange on solute transport in open-channel flow

2001 ◽  
Vol 446 ◽  
pp. 321-345 ◽  
Author(s):  
CHIU-ON NG ◽  
T. L. YIP
Keyword(s):  
Channel Flow ◽  
Water Distribution ◽  
Open Channel ◽  
Transport Coefficients ◽  
Chemical Species ◽  
Open Channel Flow ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Sorption Kinetics ◽  
Bulk Solid

A theory is presented for the transport in open-channel flow of a chemical species under the influence of kinetic sorptive exchange between phases that are dissolved in water and sorbed onto suspended sediments. The asymptotic method of homogenization is followed to deduce effective transport equations for both phases. The transport coefficients for the solute are shown to be functions of the local sediment concentration and therefore vary with space and time. The three important controlling parameters are the suspension number, the bulk solid–water distribution ratio and the sorption kinetics parameter. It is illustrated with a numerical example that when values of these parameters are sufficiently high, the advection and dispersion of the solute cloud can be dominated by the sorption effects. The concentration distribution can exhibit an appreciable deviation from Gaussianity soon after discharge, which develops into a long tailing as the solute cloud gradually moves ahead of the sediment cloud.

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