scholarly journals PENGARUH VEGETASI TERHADAP TAHANAN ALIRAN PADA SALURAN IRIGASI

2019 ◽  
Vol 2 (2) ◽  
pp. 107-113
Author(s):  
I.E. Sulastri Sihotang ◽  
Eldina Fatimah ◽  
Masimin Masimin
Keyword(s):  
Flow Velocity ◽  
Field Observation ◽  
Flow Resistance ◽  
Grid Method ◽  
Flow Depth ◽  
Secondary Channel ◽  
Irrigation Channel ◽  
Velocity Flow

Irrigation channel in D.I. Timbang Deli, Deli Serdang district Sumut province has a total area of 520 Ha and a 5000 meter long secondary channel. Irrigation channel in D.I. Timbang Deli overgrown vegetation at the base and wall of the channel so it is expected to affect roughness. The objective of the study was the flow resistance with the variation of vegetation volume to the variation of the discharge. The method used in this study is field observation by measuring flow velocity, flow depth and vegetation volume (VT) on trapezoidal tract width of 3.75 m and height of 0.90 m along 154 m. Measurements were performed on 3 points of upstream, middle and downstream channels and 5 transverse dots X1 through X5 4 times with D1 debit variation of 1.32 m³/s and D2 of 0.98 m³/s. The dominant vegetation channels are rigid. Measurement velocity using current meter while for vegetation volume (VT) using grid method. The results showed that vegetation volume VT0 (0,00 m³/0,00%), VT1 (52,417 m³/21,14%), VT2 (70,7921 m³/24,51%) and VT3 (83,053 m³/30,42%). It is seen that the increase in vegetation volume can affect the flow resistance. The result of measurement increased the resistance of flow to VT0 0,052, VT1 equal to 0,062 with percentage 16,13%, VT2 equal to 0,108 with percentage 51,85% and VT3 equal to 0,122 with percentage 57,37% atD1. Meanwhile, at D2 there is an increase of flow resistance to VT0 by 0,044, VT1 is 0,052 with percentage 15,38%, VT2 equal to 0,058 with percentage 24,14% and VT3 equal to 0,070 with percentage 37,14%. This shows that the flow resistance VT0 is smaller than the flow resistance VT1, VT2 and VT3. From the above results are expected to conduct O P channels by surrounding communities and related government.

The nature of saltation and of ‘bed-load’ transport in water

1973 ◽  
Vol 332 (1591) ◽  
pp. 473-504 ◽  
Keyword(s):  
Flow Velocity ◽  
Bed Load ◽  
Flow Depth ◽  
Mean Flow ◽  
Stream Power ◽  
Fluid Turbulence ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Mean ◽  
Mean Flow Velocity

Owing to observational difficulties the distinction between a ‘suspended’ load of solids transported by a stream and a ‘ bed-load ’ has long remained undefined. Recently, however, certain critical experiments have thrown much light on the nature of bed-load transport. In particular, it has been shown that bed-load transport, by saltation, occurs in the absence of fluid turbulence and must therefore be due to a separate dynamic process from that of transport in suspension by the internal eddy motion of a turbulent fluid. It has been further shown that the forward motion of saltating solids is opposed by a frictional force of the same order as the immersed weight of the solids, the friction coefficient approximating to that given by the angle of slip. The maintenance of steady motion therefore requires a predictable rate of energy dissipation by the transporting fluid. The fluid thrust necessary to maintain the motion is shown to be exerted by virtue of a mean slip velocity which is predictable in the same way as, and approxim ates to, the terminal fall velocity of the solid. The mean thrust, and therefore the transport rate of saltating solids, are therefore predictable in terms of the fluid velocity close to the bed, at a distance from it, within the saltation zone, of a ‘centre of fluid thrust’ analogous to the ‘centre of pressure’. This velocity, which is not directly measurable in water streams, can be got from a knowledge of stream depth and mean flow velocity. Thus a basic energy equation is obtained relating the rate of transporting work done to available fluid transporting power. This is shown to be applicable to the transport both of wind-blown sand, and of water-driven solids of all sizes and larger than that of medium sand. Though the mean flow velocity is itself unpredictable, the total stream power, which is the product of this quantity times the bed shear stress, is readily measurable. But since the mean flow velocity is an increasing function of flow depth, the transport of solids expressed in terms of total stream power must decrease with increasing flow depth/grain size ratio. This considerable variation with flow depth has not been previously recognised. It explains the gross inconsistencies found in the existing experimental data. The theoretical variation is shown to approximate very closely to that found in recent critical experiments in which transport rates were measured at different constant flow depths. The theory, which is largely confirmed by these and other earlier experiments, indicates that suspension by fluid turbulence of mineral solids larger than those of medium sands does not become appreciable until the bed shear stress is increased to a value exceeding 12 times its threshold value for the bed material considered. This range of unsuspended transport decreases rapidly, however, as the grain size is reduced till, at a certain critical size, suspension should occur at the threshold of bed movement.

scholarly journals Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation

2017 ◽  
Vol 43 (5) ◽  
pp. 981-992
Author(s):  
Xiaowei Zhou ◽  
Chunming Xia ◽  
Gandy Stephen ◽  
Faisel Khan ◽  
George A. Corner ◽  
...  
Keyword(s):  
Shear Rate ◽  
Flow Velocity ◽  
Flow Rate ◽  
Wall Shear Rate ◽  
Velocity Flow ◽  
Measured Flow ◽  
Wall Shear

scholarly journals FIELD OBSERVATION OF THE PULSATORY FLOW VELOCITY BY RADIO CURRENT METER

2008 ◽  
Vol 52 ◽  
pp. 883-888
Author(s):  
Takayuki YAMAGUCHI ◽  
Hideharu SAITOH ◽  
Shuichi MORI ◽  
Masato MORITA ◽  
Rie IWAMOTO
Keyword(s):  
Flow Velocity ◽  
Field Observation

scholarly journals Experimental Study on the Effect of Triangular Plate Barrier Height on Flow Velocity Distribution in Open Channels

2021 ◽  
Vol 2 (2) ◽  
pp. 31-36
Author(s):  
Lhiung Phung Hwa
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Open Channel ◽  
Pitot Tube ◽  
Closed Channel ◽  
Velocity Flow ◽  
Velocity Changes ◽  
Automatic Tool ◽  
Data Collection Technique ◽  
Narrow Opening

Open and closed channel flow flows are distinct, the flow in the channels will constantly change. The flow will also be altered if the water level or flow velocity changes. It was found that employing the Pitot Tube Portable yielded findings identical to those calculated by other methods. A water transfer system is made up of natural or artificial structures via which water is moved from one site to another. The carrier building may be open or closed, depending on whether you want to utilize it as a shipping or receiving location. An open channel with a relatively narrow opening at the top is known as an open conduit. The speed data collection technique is carried out vertically, with a review point as illustrated above. The velocity of the flow was measured using a Pitot Tube Portable Automatic tool. The results are entered into the Froude number (fr) after each review point to determine the type of velocity flow at each Review point. The normal flow velocity distribution pattern emerges at the measurement sites of 450 cm, 500 cm, and 550 cm.

scholarly journals Modeling of Kahayan River Bed on the Section of Kahayan Bridge in Palangkaraya City, Center of Borneo Province, Indonesia

2020 ◽  
Vol 8 (6) ◽  
pp. 383-388
Keyword(s):  
Flow Velocity ◽  
Froude Number ◽  
Flow Regime ◽  
Model Test ◽  
Low Flow ◽  
Flow Depth ◽  
City Center ◽  
River Bed ◽  
In The Beginning ◽  
Critical Type

This research intends to carry out the hydraulic model test in Kahayan River for knowing the changes of Kahayan river bed. This model uses 4 model discharge variations that are Q1= 0.798l/sec, Q2= 0.854 l/s, Q3= 0.897 l/sec, Q4= 0.994 l/sec by using the tilting slope (4.58x10-5 ). The data that are used in this model are flow depth, flow velocity, and the river bed shape after being flowed on each discharge. The result shows that based on the analysis of Froude number, it can said that the flow is as sub-critical type, however, in the beginning of flowing, fraction shows the Froude number is more than 1. This event is only happened in the upstream model. The flow with the Froude number is less than 1 is mentioned as the low flow regime. From the modeling result and it is carried out the bed river contour drawing, it is seen that the configuration of Kahayan river bed is as the ripples type

Numerical Simulations of Three Dimensional Turbulent Flows in a Shrouded Backswept Impeller at Design and Off-Design Flow Rates Using Unstructured Grid Method

2000 ◽  
Author(s):  
Chuhua Zhang ◽  
Yongmiao Miao ◽  
Chuangang Gu
Keyword(s):  
Flow Velocity ◽  
Flow Rate ◽  
Unstructured Grid ◽  
Three Dimensional ◽  
Grid Method ◽  
Main Flow ◽  
Design Flow ◽  
Radial Velocity Component ◽  
Flow Rates ◽  
Design Flow Rate

The three-dimensional turbulent flow fields in a shrouded fan impeller with backswept discharge at three operating flow rates are numerically calculated with an unstructured grid method recently developed by the authors. Reynolds-averaged Navier-Stokes (N-S) equations and k-ε equations are solved through finite volume method with pressure correction algorithm. Numerical results are presented for detailed main and secondary flow velocity. The agreements of radial velocity component at different sections at design flow rate between computations and measurements are generally good. It can be observed that different flow rates have distinctive effects on flow patterns. At design flow rate, the flow is behaved as attached flow pattern and has a relatively smooth distribution for the main flow velocity. Above the design flow rate, a sudden drop and non-smooth distribution for the main flow velocity appear at the pressure-hub corner near the impeller inlet, however, the distribution of main flow velocity becomes smooth gradually downstream. Under the design flow rate, the jet-wake structure appears obviously within the impeller passage.

scholarly journals Assessing methods for estimating roughness coefficient in a vegetated marsh area using Delft3D

2017 ◽  
Vol 19 (5) ◽  
pp. 766-783 ◽  
Author(s):  
Khalid Al-Asadi ◽  
Jennifer G. Duan
Keyword(s):  
Flow Resistance ◽  
Flow Model ◽  
Tidal Flow ◽  
Flow Dynamics ◽  
Roughness Coefficient ◽  
Flow Depth ◽  
Floodplain Vegetation ◽  
Marsh Area ◽  
Empirical Relations ◽  
Induced Flow

A Delft3D-FLOW model was used to simulate tidal flow in Davis pond marsh in Louisiana, USA. The study area is a freshwater marsh consisting of one main channel and floodplain. Vegetation-induced flow resistance greatly influences tidal flow dynamics in the marsh. This study evaluated eight approaches to estimate vegetation roughness, including two constant Manning's n values, four empirical relations for calculating n, and two methods for calculating Chezy's C values originally embedded in the Delft3D model. Simulated results of water surface elevation (WSE) were compared with the corresponding field observation at eleven stream gauges in the study area. We concluded that the roughness coefficient for vegetated area varies with time as flow depth changes. Among the selected empirical relations for the vegetation roughness, the ones accounting for the effect of the vegetation frontal area and the degree of submergence have closely matched the measurements.

scholarly journals Assessing theoretical flow velocity profile and resistance in gravel bed rivers by field measurements

2018 ◽  
Vol 49 (4) ◽  
pp. 220-227 ◽  
Author(s):  
Vito Ferro ◽  
Paolo Porto
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Froude Number ◽  
Flow Resistance ◽  
Field Measurements ◽  
Mean Flow ◽  
Gravel Bed ◽  
Wide Range ◽  
Gravel Bed Rivers ◽  
Resistance Equation

Previous studies showed that integrating a power velocity profile, deduced applying dimensional analysis and the incomplete self-similarity condition, the flow resistance equation for open channel flow can be obtained. At first, in this paper the relationship between the Γ function of the power velocity profile, the channel slope and the Froude number, which was already empirically introduced in a previous paper, is now theoretically deduced. Then this relationship is calibrated using the field measurements of flow velocity, water depth and bed slope carried out in 101 reaches of gravel bed rivers available by literature. The proposed relationship for estimating Γ function and the theoretical flow resistance equation are also tested by an independent dataset of 104 reaches of some gravel bed rivers (Fiumare) in Calabria region. Finally, the theoretically-based relationship for estimating the Γ function is calibrated by the overall available database (205 reaches). In this way the three coefficients of the theoretically based Γ function are estimated for a wide range of slopes (0.1%-6.19%) and hydraulic conditions (Froude number values ranging from 0.08 to 1.25). In conclusion, the analysis shows that the Darcy-Weisbach friction factor for gravel bed rivers can be accurately estimated by the approach based on a power-velocity profile and the theoretically-based relationship proposed for estimating Γ function. The analysis also points out a performance in estimating mean flow velocity better than that obtained in a previous study carried out by the authors.

scholarly journals The Impact of Inflow Angle on Aneurysm Hemodynamics: A Simulation Study Based on Patient-Specific Intracranial Aneurysm Models

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiao Mo ◽  
Qianqian Meng ◽  
Xinjian Yang ◽  
Haiyun Li
Keyword(s):  
Flow Velocity ◽  
Image Data ◽  
Patient Specific ◽  
Rupture Risk ◽  
Hemodynamic Changes ◽  
Structure Interaction ◽  
Velocity Flow ◽  
Hemodynamic Characteristics ◽  
The Impact ◽  
Fully Coupled

The inflow angle of intracranial aneurysms (IAs) can impact the hemodynamics of IAs, therefore it is likely to contribute to IA clinical rupture risk stratification. This study aimed to assess the effect of inflow angle on the hemodynamics of IAs, as well as its potential ability to predict IA rupture risk. A novel algorithm was developed to build a series of inflow angle models on patient-specific IA models, which were reconstructed from IA 3DRA image data of eleven clinical patients. Fully coupled fluid-structure interaction (FSI) simulations were performed to quantify hemodynamic characteristics of the established IA models with various inflow angles. Hemodynamic parameters including wall shear stress (WSS), flow velocity, flow pattern, inflow zone, impingement region, pressure, and energy loss (EL) were calculated and analyzed. It was demonstrated from the analysis that a rise in the IA inflow angle is associated with the following hemodynamic changes: more direct blood flowed into the aneurysm sac, higher velocity at the upside of the aneurysm, upregulated flow velocity and WSS in the aneurysm, more complicated flow patterns, extended inflow zone, the impingement region moving upward from the neck to the apex of the aneurysm, and higher WSS and larger flow velocity at the inflow zone of the IAs. Therefore, the proposed method may be helpful in exploring the hemodynamic variations of IAs with inflow angles. The findings could be conducive to hemodynamic studies on the association between IA inflow angle and its rupture risk.

scholarly journals Effects of Simulated Gravel on Hydraulic Characteristics of Overland Flow Under Varying Flow Discharges, Slope Gradients and Gravel Coverage Degrees

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaona Liu ◽  
Dengxing Fan ◽  
Xinxiao Yu ◽  
Ziqiang Liu ◽  
Jiamei Sun
Keyword(s):  
Water Conservation ◽  
Flow Resistance ◽  
Overland Flow ◽  
Hydraulic Parameters ◽  
Flow Depth ◽  
Hydraulic Characteristics ◽  
Power Functions ◽  
Laboratory Flume ◽  
Ecological Construction ◽  
Soil And Water

AbstractTo quantify the hydraulic characteristics of overland flow on gravel-covered slopes, eight flow discharges (Q) (8.44–122 L/min), five slope gradients (J) (2°–10°) and four gravel coverage degrees (Cr) (0–30%) were examined via a laboratory flume. The results showed that (1) gravel changed flow regime. Gravel increased the Reynolds number (Re) by 2.94–33.03%. Re were less affected by J and positively correlated with Cr and Q. Gravel decreased the Froude number (Fr) by 6.83–77.31%. Fr was positively correlated with Q and J and negatively correlated with Cr. (2) Gravel delayed the flow velocity (u) and increased the flow depth (h) and flow resistance (f). Gravel reduced u by 1.20–58.95%. u was positively correlated with Q and J and negatively correlated with Cr. Gravel increased h by 0.12–2.41 times. h was positively correlated with Q and Cr and negatively correlated with J. Gravel increased f by 0.15–18.42 times. f were less affected by J, positively correlated with Cr and negatively correlated with Q. (3) The relationships between hydraulic parameters and Q, J and Cr identified good power functions. Hydraulic parameters were mainly affected by Cr. These results can guide the ecological construction of soil and water conservation.

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