ORIGINAL_ARTICLE
Experimental investigation on controlling of sedimentary density current using constructing obstacle
Density currents are the main cause for sediment transport in dams reservoirs and seas deltas. One of the problem solution is to reduce or eliminate the effect of them using completely block the density current and as a result the sediment settle far away from the dam in strolling of density current, some experiment were carried out on a flume in water Sciences Engineering Laboratory, Shahid Chamran University of Ahwaz. In this research density current were provided using sediments with d50 of 28.9 µm and passing flow from obstacle was investigated under different bed slopes and discharges. The obtained results show that the effect of obstacle for sub-critical flow is more than supercritical flow. However it was found that even for supercritical flow obstacles are considerably effective on preventing of density current flow.
https://jise.scu.ac.ir/article_13475_f6eb13eb916813a59618826e9d9f08d0.pdf
2010-10-23
1
15
10.22055/jise.2010.13475
Density current
Sediment transport
dam reservoirs
seas deltas
Seyed Amin
Asghari Pari
asghari.amin56@gmail.com
1
Ph.D. Graduated, Department of Water Structure, Shahid Chamran University, Ahwaz, Iran
LEAD_AUTHOR
Seyed Mahmood
Kashefi Pour
kashefipour@excite.com
2
Professor, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
AUTHOR
Mehdi
Ghomeshi
m.ghomeshi@yahoo.com
3
Professor, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
AUTHOR
ORIGINAL_ARTICLE
Determiation of friction factor in river banks and floodplains with non-submerged vegetation
Because of vegetation flexibility in flood plains and river banks, friction factors vary in these areas and are function of vegetation characteristics and flow conditions. Due to being of important structures such as water pumping stations, Roads, water treatment plans and wastewater, fish pools in the river banks and construction of structures such as bridges and diversion dams on them, study of river behavior especially effect of vegetation on flow capacity is very important. Purpose of this research was to obtain relationships and values suitable for vegetation roughness coefficients in the flood plains and river banks for Non-submerged conditions. To do research first identified and selected parameters effect on flow, including vegetation type, velocity, submerged ratio, density and absorption surface momentum and using dimensional analysis relations between roughness coefficient and dimensionless were obtained. Then 182 experiments were conducted on a laboratory flume and effect of parameters on the roughness coefficient was evaluated. By using of results, relations obtained from dimensional analysis were calibrated. Research results can be possible to calculate the friction factors with have above parameters. Roughness coefficients reduce with increasing of flow rate to be nonlinear and severely, for example increase velocity from 0.2 m/s to 2 m/s make Manning’s coefficient reduces to one third of the first case. But reducing amount of coefficient with decrease of submergence ratio and density compared with the velocity is low and decreasing trend is linear trend, For example if density was reduced from greater category to lower category, value of manning coefficient reduce maximum by ten percent.
https://jise.scu.ac.ir/article_13476_3d5725e766255bff1c4f5a6505ed159a.pdf
2010-10-23
17
28
10.22055/jise.2010.13476
Friction Factors
Vegetation
Flexibility
Non-Submerged
Khosro
rikvaandi
drik_khosro@yahoo.com
1
Ph.D. Graduated, Department of Irrigation, Science and Research Branch, Islamic Azad University ,khouzestan, Iran
LEAD_AUTHOR
Alireza
Masjedi
drmasjedi.2007@yahoo.com
2
Department of Water Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.
AUTHOR
Mahmood
Bina
3
Associate Professor, Science and Research Branch, Islamic Azad University ,khouzestan, Iran
AUTHOR
ORIGINAL_ARTICLE
Determination of the drought periods by analyzing the hydrometeorological data
This article presents an overview of the water resources available in Iran on one hand and Urmia lake catchments area, situated on the North-West of this country on the other. Water balances are presented for the Urmia lake catchments area and the water supply and consumption patterns in the Iranian main river basins. The drought periods occurrences have been analyzed using the forecasting methods and correlation laws between the discharges and the precipitation data measurements for the Adji-chai river, which is a river most representative of the Arid and Semi-arid region. The results obtained from using forecasting methods in data analysis indicated that drought phenomenon in Tabriz region and in general in Iran, is resulted from irregular time and spatial precipitation distributions in one hand, and severely negative fluctuations in precipitations and consequently highly reduced river flows on the other.
https://jise.scu.ac.ir/article_13477_25486b335f6ecbf26cb56f07d5ae236c.pdf
2010-10-23
27
41
10.22055/jise.2010.13477
Drought periods
Hydrometeorology
Urmia lake
Water balance
Forecasting methods
Correlation laws
Adji-chai river
Yousef
Hassan Zadeh
yhassanzadeh@tabrizu.ac.ir
1
Professor, Faculty of Civil Engineering, University of Tabriz, Iran
AUTHOR
ORIGINAL_ARTICLE
Wall and bed shear stress in smooth rectangular channels
This Study reports on experiments concerning the boundary shear stress and boundary shear force distributions in a smooth rectangular channel. The boundary shear stresses were measured with a 4-mm outside diameter Preston tube in conjunction with a differential pressure transducer. The calibration curves of Patel (1965) were used to convert pressure reading to boundary shear stresses. Nonlinear regression-based equations are drive from experimental analysis to determine percentage of the total shear force carried by the walls and mean wall and bed shear stresses around wetted perimeter. The proposed equations compared to previous researches are shown to higher correlation coefficient and smaller standard deviation. Furthermore, single variable equations are introduced in the paper indeed an advantage compared to that of other studies.
https://jise.scu.ac.ir/article_13478_49b4b9446b9854e97de1fba645a18a60.pdf
2010-10-23
43
52
10.22055/jise.2010.13478
Shear Stress
Shear force
Preston Tube
Babak
Lashkarara
babak_lashkarara@yahoo.com
1
Ph.D. Graduated, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
LEAD_AUTHOR
Manoochehr
Fathi Moghadam
fathi49@gmail.com
2
Professor, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
AUTHOR
Hossain
Mohammad Vali Samani
hossein.samani@gmail.com
3
Professor, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
AUTHOR
ORIGINAL_ARTICLE
Sediment particles incipient motion criteria at closed box conduits
Deposition of sediment inside the conduit structures; eg inverted siphon; reduces the flow cross section area and increase the flow roughness which causes reduction of flow discharge passing through the conduit. In order the structure to function properly, the structure should design not to allow any sediment particle to deposit. Or if deposited, it can be possible to remove them by the action of flow. Among the methods in which can be achieved such goals is to design the structure in such a way that the flow velocity to be greater than incipient motion velocity. There are many relations to obtain the incipient motion velocity of sediment particles on the bed or slope of an open channel. However for the case of closed conduits under low pressure little information is available. Such criterion is useful for sewer cleaning too. To determine the criteria for determining the incipient motion velocity at closed box conduits this study was conducted. To do so first a general relationship was developed by applying the dimensional analysis and then experimental tests were conducted to obtain data. In these tests five different sediment particle sizes, 0.5, 0.7, 1.0, 2.0 and 3.2 millimeters under four different bed slopes 0.0, 8.0, 16, and 24 degrees were conducted. By analyzing of these data design charts were developed. From these curves, the incipient motion velocity can be determined. The results were compared with the results of other investigators. The application of this study in some of the inverted siphons in Khuzestan province of Iran has been presented.
https://jise.scu.ac.ir/article_13479_6e26858185594976d1ae9b0b2c608087.pdf
2010-10-23
51
61
10.22055/jise.2010.13479
Incipient motion
Box cross section conduits
Sediments
Inverted Siphon
Sedimentation control
Hossein
khozeymehnezhad
hkh359@gmail.com
1
Ph.D. Student, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
LEAD_AUTHOR
mahmood
shafai bajestan
m_shafai@yahoo.com
2
Professor, Department of Water Structures, Shahid Chamran University, Ahvaz, Iran
AUTHOR
ORIGINAL_ARTICLE
Effect of tailwater depth on local scour downstream of horizontal jets
In this paper the results of an experimental study on the effect of tailwater depth on the mechanism of scouring downstream of hydraulic jumps is presented. Totally, 53 tests with 12 hours run time were carried out under various tailwater depths ranging from 14.2 to 32.5 cm for 5 different densimetric Froude numbers. The results show that the tailwater depth has a significant role in the scouring process and its effect depends on the magnitude of densimetric Froude numbers. For high values of the Froude number, there is a critical submergence value, where the minimum depth of the scour hole is occurred. An empirical equation is proposed to determine this critical submergence factor. Considering the mechanism of a submerged jet issuing from a sluice gate opening and passing a sudden step, a new approach is proposed to justify the presence of critical submergence factor. Comparing the present results with those of previous studies shows that the length of apron is also an important factor in the scouring process. Non-dimensional graphs are presented to determine the magnitude of scour depth for different tailwater depth and Froude numbers. Finally, it was found that the maximum scour depth and the dune height are more impressible to the variations of the tailwater depth than scour hole length.
https://jise.scu.ac.ir/article_13480_ada7c7f604cf1040da03cdf88b8296dc.pdf
2010-10-23
63
74
10.22055/jise.2010.13480
Local scour
Tailwater depth
Hydraulic jump
Critical Submergence factor
Mohammad Hosain
Omid
hhamidifar@ut.ac.ir
1
Associate professor, Department of Irrigation and Reclamation Eng., University of Tehran, Karaj, Iran
LEAD_AUTHOR
Hossein
Hamidifar
hamidifar@shirazu.ac.ir
2
Ph.D. Student, Water Structure, Department of Irrigation and Reclamation Eng., Tehran University, Karaj, Iran
AUTHOR
Mohsen
Nasr Abadi
3
M.Sc. Graduate, Water Structure, Department of Irrigation and Reclamation Eng., Tehran University, Karaj, Iran
AUTHOR
ORIGINAL_ARTICLE
The influence of time scale in free surface flow simulation using Smoothed Particle Hydrodynamics (SPH)
In hydrodynamic and hydraulic science, free surface flows are important but they are difficult to simulate because boundary conditions are required on an arbitrarily moving surface. Smoothed particle hydrodynamics (SPH) is a meshfree, Lagrangian particle method for modeling free surface flows such as dam break. One of problems in SPH is time consuming calculations in cases that they occurrence time are large. They need computers with strong CPU and memory. Recently, the parallel is used in this situation. In this paper, the influence of time scale in free surface flow simulation using SPH is considered. Dam break simulation with SPH in different scales is investigated and time scale influence is then obtained. For SPH model verification, the results were compared with experimental and numerical results of pervious researches. The dam break results as free surface flow show that the model with less scale model has less time of occurrence. Thus, the computer run time was decreased. The relation between two scales in dam break simulation indicates that the Froude law for free surface flow is valid. For models with scales of 3 and 6 with equal number of particles, the time of occurrence and computation were decreased about 42% and 59%, respectively. Therefore the computers run time can be decreased when this new-proposed scheme isused.
https://jise.scu.ac.ir/article_13481_abc1042396be94064b469f493fe1c8e5.pdf
2010-10-23
75
92
10.22055/jise.2010.13481
Dam break
Time scale
Smoothed Particle Hydrodynamic
Free surface flow simulation
Seyedeh Laila
Razavi Toosi
1
Ph.D. Student of Water Structure Department, Tarbiat Modares University,Tehran
LEAD_AUTHOR
Seyed Ali
Ayyoubzadeh
ayyoub@modares.ac.ir
2
Associate Professor of Water Structure Department, Tarbiat Modares University, Tehran
AUTHOR
Ali Reza
Vali Zadeh
3
Assistant Professor, Lorestan University, Khoramabad
AUTHOR
ORIGINAL_ARTICLE
Experimental investigation on the effect of curvature of bend on bed topography in 90 degree bend
Rivers are main sources of water supply. Recognition of rivers behavior and their changes, particularly in Curved channels, is critical. In this paper, results of experiments on scour pattern in a 90 degree bend are discussed. Experiments have been carried out in a channel with three different radiuses of curvatures, including mild, moderate and steep. Bed topography has been measured by Laser Bed Profiler. Comparison between different lateral sections, longitudinal sections and bed topography has been made and scouring pattern is analyzed. The results indicate that reduction of radius of curvature of the bend leads to increase of bed topography changes and sedimentation and scouring rates. Also, scour can be seen along downstream straight channel and near the outer bank; however, this is more evident in the steeper bend.
https://jise.scu.ac.ir/article_13482_8df123cfb57573fa5f8ce2d482911051.pdf
2010-10-23
93
112
10.22055/jise.2010.13482
Scour pattern
90 Degree bend
Bed topography
Radius of curvature
Mohammad
Vaghefi
vaghefi@pgu.ac.ir
1
Assistant Professor, Department of Civil Engineering, Persian Gulf University, Bushehr,Iran
LEAD_AUTHOR
Masoud
Ghodsian
ghodsyank.modares@ac.ir
2
Professor, Water Engineering Research Center, Tarbiat Modares University, Tehran, Iran
AUTHOR
ORIGINAL_ARTICLE
Comparison of Fuzzy and ANN models performance for monthly flow forecast using short time data
Regarding the bottom outlet gates, the optimal hydraulic design to ensure non-occurrence of destructive vibrations is very important. Forces inserted into the gates due to the flow with high hydrostatic pressure under the gates may cause creation of damage on the lower edge of gates. Compressive hydrostatic force along with the gate weight and friction forces determine the required powers for down-pull (or uplift) of the gates which is also affected by the geometric shape and flow passing under the gates. The existence of high pressure flow in the upstream of bottom outlet gates, as well as the small quantities of gate opening compared to the head water, may cause using common theoretical methods result in significant errors in the determination of different involved parameters. Therefore there is a need for accurate laboratory studies. In this paper, the results of the study on the physical model of bottom channel and service and emergency gates of Narmasheer Dam is presented. Also the results of measurements of exerted forces gate and vibrations into the gates are provided. The necessary tests have been made, so that using the measured pressure distribution on the gates, vertical forces and maximum damage in both normal head tank and various gate openings, were determined respectively. The exerted forces were calculated based on the use of pressure distribution obtained by piezometers installed above and under the gates. In this study, the maximum horizontal force appears on the 2 percent gate opening and is equivalent to 2410 (KN). The maximum horizontal force into the emergency gate has also occurred in the initial gate opening situation with a value of 2507 (KN). The experimental results also indicated that the maximum operation frequency of vibration due to the high pressure flow in the bottom outlet channel is 80 per second. The tests showed that by increasing the diameter of gate lift arm, the frequency of vibration can be controlled.
https://jise.scu.ac.ir/article_13483_22d0c7aa7e4faccecfc989392344405d.pdf
2010-10-23
113
126
10.22055/jise.2010.13483
Vibration
Emergency gate
Service gate
Bottom outlet
Physical model
Down pull force
Narmasheer dam
Sedigheh
Anvari
anvari.t@gmail.com
1
Ph.D. Student of Water Structure Department, Tarbiat Modares University, Tehran
LEAD_AUTHOR
Saeid
Morid
morid_sa@modares.ac.ir
2
Associate Professor of Water Resource Engineering, Tarbiat Modares University, Tehran
AUTHOR
Bahram
Saghafian
saghafian@scwmri.ac.ir
3
Professor of Soil and Water Conservation Research Institute, Tehran
AUTHOR
ORIGINAL_ARTICLE
Influence of the steeped spillway slope on the number of optimal steps
In the present study 54 step spillways make of ple Glass, 5 discharges (10, 20, 30, 40 and 50 l/s/m) and 3 slopes, z=1.7 , z=2 and z=2.5 (totally 275 experiments were conducted). Finding of the present study are as follows: 1- Performed modeling observations revealed that the relative energy dissipation along with spillway will be decreased with increasing discharge. 2- It is shown that energy dissipation is increase with increasing step numbers, but energy dissipation will be stopped in a certain number of steps. 3- According to presented study, optimal number of steps base on different values of yc/h and Froude Number is determined for the maximum energy dissipation. It is shown that optimal number of steps is affected by slope of spillway. Increasing spillway slope causes more energy dissipation.
https://jise.scu.ac.ir/article_13484_dd1bb5f71369ad4e999b454fa04ef44b.pdf
2010-10-23
127
140
10.22055/jise.2010.13484
Stepped spillway
Maximum energy dissipation
Number of optimal step
Physical modeling
Siavash
Heydari orojlo
heidari.av@gmail.com
1
M.Sc. graduate, Department of Water Science Engineering, Shahid Chamran University, Ahvaz
LEAD_AUTHOR
Seyed Habib
Mousavi Jahromi
dr_musavi@yahoo.com
2
Associate Professor Water Science Engineering Faculty, Shahid Chamran University, Ahvaz
AUTHOR
Arash
Adib
arashadib@scu.ac.ir
3
Assistant Professor, Civil Engineering Department, Shahid Chamran University, Ahvaz
AUTHOR
ORIGINAL_ARTICLE
Experimental investigation of flow characteristics on discharge coefficient over compound rectangular broad-crested weir
Compound weirs are composed of two sections: 1.Lower entrance section 2.Upper entrance section. Lower entrance section is designed in different shapes such as rectangle, trapezoid, … and it works singly in low discharges. Flow discharge is measured accurately and sensitively according to weir shape in such a condition. In high discharges, upper entrance section prevents water surface from having remarkable increase at upstream of weir and provides the possibility of discharge measurement with acceptable accuracy. In this study, flow over 15 rectangular broad-crested weirs was simulated with different sizes in central width of weir, height and length of weir using experimental models and the effects of these parameters on discharge coefficient, velocity coefficient, and modular limit were investigated. Results show that with increasing dimensionless parameter: head to weir length (h1/L), discharge coefficient (Cd) increase, in other words, Cd in single section (h1/L)<0.24 is lower than compound weir section. Also this condition for h1/p<0.94 (p is weir height) is true. In compound weir condition, reduction in central cross section width and weir height causes to increase modular limit.
https://jise.scu.ac.ir/article_13485_9da40fe2a3e98da28f9ada4a9ea79fd2.pdf
2010-10-23
141
156
10.22055/jise.2010.13485
Compound broad-crested weir
Discharge Coefficient
Approach velocity coefficient
Modular limit
Sanaz
Pour Eskandar
1
M.Sc. Student, Department of Water Eng., University of Tabriz, Iran
LEAD_AUTHOR
Farzin
Salmasi
salmasi@tabrizu.ac.ir
2
Assistant Professor, Department of Water Engineering, University of Tabriz
AUTHOR
Ali
Hossai Zadeh Dalir
ahdalir@tabrizu.ac.ir
3
Associated Professor, Department of Water Engineering, University of Tabriz
AUTHOR
Davood
Farsadi Zadeh
farsadi@tabrizu.ac.ir
4
Associated Professor, Department of Water Engineering, University of Tabriz
AUTHOR
ORIGINAL_ARTICLE
Estimating near-saturated soil moisture curve using disc-permeameter data and comparing it with laboratorial method
Nitrogen (N) loss from irrigated cropland, especially in rice paddies, results in low N-use efficiency and groundwater contamination. Soil conditions that increase ammonium and nitrate ion retention alleviate these problems. Clinoptilolite, a naturally occurring zeolite with high ion-exchange capacity, may be used to adsorb ammonium and retard excess leaching of nitrate. The objectives of this research were to determine the effects of different rates of Na-zeolite application (0, 2, 4, 8 and 16 g/kg soil) on pore water velocity and leaching of ammonium and nitrate applied as ammonium nitrate fertilizer to a silt loam soil at a rate of 350 kg N/ha under saturated conditions similar to that of a rice paddy. The results indicated that Na-zeolite applications of 2, 4 and 8 g/kg soil increase the pore water velocity by 5.0%, 19. 9, 68.0 and 58/6% compared with the control treatment, respectively. The maximum relative concentration (c/co) all treatments for the nitrate breakthrough curve (BTC) occurred at pore volume of about 0.5. When applying 39.1 cm of leaching water, leached nitrate by 86.9%, 66.00% and 48.5% of total applied nitrate at the soil surface with zeolite applications of 2, 4 and 8 g/kg soil, respectively. Although the ammonium discharged from all treatments was negligible (3.95, 3.48, 3.13 and 2.28 percent of total applied ammonium at the soil surface), the statistical analysis indicated significant differences among treatments that received zeolites. The relationship between the hydrodynamic dispersion coefficient (D) of nitrate and pore water velocity (v) was not linear and by increasing zeolite application to the soil, the value of D increased as well.
https://jise.scu.ac.ir/article_13486_725559e16aced589b9b470279a17b33b.pdf
2010-10-23
157
166
10.22055/jise.2010.13486
Zeolite
nitrate
Ammonium
Breakthrough curve
Hydrodynamic Dispersion
sareh
tangsir
saretangsir@yahoo.com
1
M.Sc. Student, Department of Irrigation and Drainage, Shahid Chamran University, Ahvaz
LEAD_AUTHOR
Heaidar ALi
Kashluli
hkashkuli@yahoo.com
2
Professor, Department of Irrigation and Drainage, Shahid Chamran University, Ahvaz
AUTHOR
Hadi
Moazed
hmoazed955@yahoo.com
3
Assistant Professor, Department of Irrigation and Drainage, Shahid Chamran University, Ahvaz
AUTHOR