scholarly journals Flow velocity behavior programming on open channel bends

2021 ◽  
Vol 878 (1) ◽  
pp. 012049
Author(s):  
S Setiyadi
Keyword(s):  
Flow Velocity ◽  
Transverse Direction ◽  
Open Channel ◽  
Transverse Velocity ◽  
River Channel ◽  
River Channels ◽  
Flood Prevention ◽  
Channel Bend ◽  
Secondary Velocity

Abstract Flow velocity on open channel bends generally experiences additional velocity which is called secondary velocity. This paper aims to analyse and calculate the velocity that occurs in an open channel bend in general. The calculation that the writer uses is the calculation with fortran programming, in a case study of a river that bends, where the variables that must be present are given. The results of calculations and measurements of Secondary Speeds that occur at channel bends in this Open Channel will be very useful for river channel improvement or flood prevention in river channels, especially on existing bends. The conclusion is that at the bend of an open channel or river, there will be an increase in flow velocity in the transverse direction. This additional velocity is caused by the additional secondary velocity, namely the transverse velocity.

scholarly journals Landscape Design of River Channels in Small Towns based on Regional Culture-Case Study of Landscape Design of Duohua River

2018 ◽  
Vol 206 ◽  
pp. 01010 ◽  
Author(s):  
Man Lu ◽  
Chuyuan Wen ◽  
Chuanyue Wang
Keyword(s):  
Social Life ◽  
Small Towns ◽  
Landscape Design ◽  
River Channel ◽  
Local History ◽  
Regional Culture ◽  
River Channels ◽  
Flood Prevention ◽  
Treatment Measures

Water is the vital source of life while river channels constitute the arteries of the earth. As a key element of eco-structure of the Landscaping system, river plays a significant role in social life. Current river channels in small towns are managed only to achieve the traditional functions of flood prevention and irrigation while river channel landscape construction is confronted with problems such as replicating landscapes and degradation of ecological environment. River channel landscape should receive increasing attention after taking treatment measures including sewage interception, dredging, base soil treatment and revetment repair. This study offers ideas and strategies for landscaping designs of rivers in small towns that realize the value of regional culture in contemporary times on the basis of taking root in the concrete settings of the locations and the form of the design subjects in light of landscaping practices of Duohua River in Longli County which comb through regional elements and selectively keep some of them in the principle of respecting local history, natural conditions and culture in an effort to build a river landscape that represents regional culture and meets the requirements for sustainable development so that both the function and landscaping beauty can be better integrated.

scholarly journals Numerical Simulation of Effects of River Reconstruction on Flooding: A Case Study of the Ba River, China

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Haixiao Jing ◽  
Yongbiao Lang ◽  
Xinhong Wang ◽  
Mingyang Yang ◽  
Zongxiao Zhang
Keyword(s):  
Flow Velocity ◽  
Eddy Currents ◽  
Human Life ◽  
River Channel ◽  
Computational Domain ◽  
River Channels ◽  
One Dimensional ◽  
Local Reconstruction ◽  
Before And After ◽  
Flood Flow

The local reconstruction of river channels may pose obstacles of flood flow, local eddy currents, or high flow velocity which pose potential threats to human life and infrastructures nearby. In the design of such projects, the effects of local reconstruction of the river channel on flooding are often evaluated by the one-dimensional method, which is based on the formula of one-dimensional nonuniform flow. In this study, a two-dimensional hydrodynamic model based on shallow water equations is employed to investigate the impacts of river reconstruction on flooding in the Ba River, China. The finite volume method and an unstructured triangular mesh are used to solve the governing equations numerically. The numerical model is validated by comparison with the results of a physical model of 1 : 120 scale. The backwater effects and impacts of flood flow fields under two flood frequencies are analyzed by comparing the numerical results before and after local reconstruction. The results show that the backwater length under both 10-year and 100-year floods can be reached up to the upstream boundary of the computational domain. However, the maximum water level rises are limited, and the levees in this river channel are safe enough. The flow velocity fields under both floods are changed obviously after local reconstruction in the Ba River. Areas with the potential for scour and deposition of the river bed are also pointed out. The findings of this study are helpful for the evaluation of flood risks of the river.

scholarly journals Study on Flow Velocity Distribution in Open Channel With Flexible Vegetation

2021 ◽  
Vol 12 ◽  
Author(s):  
Shiyu Wang ◽  
Yi Zhou ◽  
Tongshu Li ◽  
Song Li ◽  
Mingwu Zhang ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Flow Measurement ◽  
Open Channel ◽  
Maximum Flow ◽  
Distribution Model ◽  
Turbulence Structure ◽  
River Channels ◽  
Microscopic Mechanism ◽  
Flexible Vegetation

Ecological management of river channels is a hot topic for current sustainable development and flow measurement of ecological river is an important part. In this article, a flow velocity distribution model of the channel containing flexible vegetation is constructed from the vegetation riverbed theory and the bursting phenomenon to reveal the microscopic mechanism of the flow velocity distribution in the upper layer of vegetation. In the vegetation riverbed law, the effect of flexible vegetation is evaluated by the mixed length formula. The bursting phenomenon law considers the influence of the channel sidewalls on the flow and a two-dimensional velocity model is established by introducing the concept of average turbulence structure. The mechanism of the downward shift of the maximum flow velocity point on the channel sidewall is explained. The verification of the calculated velocity profiles is carried out based on data obtained in laboratory experiments. The results show that the combination of the two models can well describe the velocity distribution of the whole channel. At the end, the phenomenon of flow velocity zoning in open channel is discussed, which provides a solution for flow measurement in ecological channel.

scholarly journals A Conflict between Traditional Flood Measures and Maintaining River Ecosystems? A Case Study Based upon the River Lærdal, Norway

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1884
Author(s):  
Ana Juárez ◽  
Knut Alfredsen ◽  
Morten Stickler ◽  
Ana Adeva-Bustos ◽  
Rodrigo Suárez ◽  
...  
Keyword(s):  
Remote Sensing Data ◽  
Freshwater Ecosystems ◽  
River Channel ◽  
Flood Mitigation ◽  
Mitigation Measures ◽  
Flood Events ◽  
Protection Measures ◽  
River Ecosystems ◽  
Hydraulic Models

Floods are among the most damaging of natural disasters, and flood events are expected to increase in magnitude and frequency with the effects of climate change and changes in land use. As a consequence, much focus has been placed on the engineering of structural flood mitigation measures in rivers. Traditional flood protection measures, such as levees and dredging of the river channel, threaten floodplains and river ecosystems, but during the last decade, sustainable reconciliation of freshwater ecosystems has increased. However, we still find many areas where these traditional measures are proposed, and it is challenging to find tools for evaluation of different measures and quantification of the possible impacts. In this paper, we focus on the river Lærdal in Norway to (i) present the dilemma between traditional flood measures and maintaining river ecosystems and (ii) quantify the efficiency and impact of different solutions based on 2D hydraulic models, remote sensing data, economics, and landscape metrics. Our results show that flood measures may be in serious conflict with environmental protection and legislation to preserve biodiversity and key nature types.

scholarly journals Fuzzy rules based model for solute dispersion in an open channel dead zone

2002 ◽  
Vol 4 (1) ◽  
pp. 39-51
Author(s):  
Helen Kettle ◽  
Keith Beven ◽  
Barry Hankin
Keyword(s):  
Finite Volume ◽  
Fuzzy Number ◽  
Open Channel ◽  
Transverse Velocity ◽  
Dead Zone ◽  
Fuzzy Rules ◽  
Turbulent Velocity ◽  
Velocity Fluctuations ◽  
Laboratory Flume ◽  
The Mean

A method has been developed to estimate turbulent dispersion based on fuzzy rules that use local transverse velocity shears to predict turbulent velocity fluctuations. Turbulence measurements of flow around a rectangular dead zone in an open channel laboratory flume were conducted using an acoustic Doppler velocimeter (ADV) probe. The mean velocity and turbulence characteristics in and around the shear zone were analysed for different flows and geometries. Relationships between the mean transverse velocity shear and the turbulent velocity fluctuations are encapsulated in a simple set of fuzzy rules. The rules are included in a steady-state hybrid finite-volume advection–diffusion scheme to simulate the mixing of hot water in an open-channel dead zone. The fuzzy rules produce a fuzzy number for the magnitude of the average velocity fluctuation at each cell boundary. These are then combined within the finite-volume model using the single-value simulation method to give a fuzzy number for the temperature in each cell. The results are compared with laboratory flume data and a computational fluid dynamics (CFD) simulation from PHOENICS. The fuzzy model compares favourably with the experiment data and offers an alternative to traditional CFD models.

Kissimmee River restoration: a case study

2002 ◽  
Vol 45 (11) ◽  
pp. 55-62 ◽  
Author(s):  
P.J. Whalen ◽  
L.A. Toth ◽  
J.W. Koebel ◽  
P.K. Strayer
Keyword(s):  
Ecological Integrity ◽  
Flow Characteristics ◽  
River Channel ◽  
Floodplain Wetlands ◽  
Water Control ◽  
Control Structures ◽  
Meandering River ◽  
Hydrologic Processes ◽  
Kissimmee River

Channelization of the Kissimmee River transformed a 167 km meandering river into a 9 metre deep, 75 metre wide, 90 km drainage canal (C-38) that is compartmentalized with levees and water control structures into a series of five stagnant pools. Channelization dramatically changed water level and flow characteristics, drained 21,000 hectares of floodplain wetlands and severely impacted fish and wildlife populations. A $500 million dollar restoration project will restore the ecological integrity of the river-floodplain system by reconstructing the natural river channel and reestablishing hydrologic processes. Sixty expectations have been established to quantify the ecosystem's recovery. The first phase of reconstruction was completed in February 2001 and included movement of 9.2 million cubic metres of earth to backfill 12 km of C-38, the explosive demolition of one water control structure, construction of two sections (2.4 km) of new river channel, and reestablishment of 24 contiguous km of river. Numerous social, political, and technical challenges have been encountered during the project's evolution. Recommendations are provided for future restoration projects.

scholarly journals Experimental Investigations of Interactions between Sand Wave Movements, Flow Structure, and Individual Aquatic Plants in Natural Rivers: A Case Study of Potamogeton Pectinatus L.

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1166 ◽  
Author(s):  
Łukasz Przyborowski ◽  
Anna Łoboda ◽  
Robert Bialik
Keyword(s):  
Flow Velocity ◽  
Three Dimensional ◽  
Potamogeton Pectinatus ◽  
Sand Wave ◽  
Experimental Investigations ◽  
Cross Sectional ◽  
Bending Tests ◽  
Long Duration ◽  
Elevation Changes

Long-duration measurements were performed in two sandy bed rivers, and three-dimensional (3D) flow velocity and bottom elevation changes were measured in a vegetated area and in a clear region of a river. Detailed flow velocity profiles downstream and upstream of a single specimen of Potamogeton pectinatus L. were obtained and the bed morphology was assessed. Potamogeton plants gathered from each river were subjected to tensile and bending tests. The results show that the existence of the plants was influenced by both bottom and flow conditions, as the plants were located where water velocity was lower by 12% to 16% in comparison to clear region. The characteristics of the flow and sand forms depended on the cross-sectional arrangement of the river, e.g., dunes were approximately four times higher in the middle of the river than in vegetated regions near the bank. Furthermore, the studied hydrophytes were too sparse to affect water flow and had no discernible impact on the sand forms’ movements. The turbulent kinetic energy downstream of a single plant was reduced by approximately 25%. Additionally, the plants’ biomechanical characteristics and morphology were found to have adjusted to match the river conditions.

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