انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Effect of Nominal Stone Diameter on Stability of Reshaping Berm Breakwaters
بررسی تاثیر قطر اسمی سنگ در پایداری موج شکن های سکویی
1
14
85492
10.30482/jhyd.2011.85492
FA
مهدی
شفیعی فر
علی
مطلبی
Journal Article
2011
03
23
Berm breakwaters are structures that reshape under waves action and reach to a stable profile. In this<br />type of breakwaters the units of the armor layer are allowed to move in order to take a final form<br />without changing the serviceability performance of the structure. The remaining berm width - after<br />rescission - is the main criterion for stability of these structures. If the rescission become more than the<br />initial berm width, the breakwater will be unstable and failure will occur.<br />In this paper the effect of nominal diameter on stability of reshaping berm breakwaters is investigated<br />by experimental studies. In order to consider the effect of this parameter in comparison with other<br />parameters, 120 tests have been carried out in the wave flume of Tarbiat Modares University<br />Hydraulic Laboratory. The waves in all tests are irregular waves conforming JONSWAP spectral<br />energy. The amount of is assumed for graining.<br />Results indicate that water depth has a considerable effect on berm rescission comparing to nominal<br />diameter. However, the initial berm width has the same effect as nominal diameter. The results also<br />show that by raising the position of berm to water level, rescission effect is reduced. On the other hand<br />by decreasing nominal diameter and increasing the initial berm width the same percentage of<br />rescission could be expected.
https://jhyd.iha.ir/article_85492_3ba27b4420e0f4a18ba160c58874994b.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Determination of Rivers` Flood Plain Risk`s Level by Multi Criteria Decision Making
تعیین سطح خطر سیل رودخانه ها در نواحی تحت تاثیر با استفاده از روش های تصمیم گیری چندمعیاره
15
29
85493
10.30482/jhyd.2011.85493
FA
پوریا
جوان
مهدی
میرزائی
ابراهیم
جباری
Journal Article
2011
03
23
Flood plain is the preferred place for agricultural and other socio-economic activities. High density<br />flood plain’s residential region shows this fact. These advantages encourage societies to invade river’s<br />bed and right-of-way. Lots of changes occur due to this invasion and cause some morphological and<br />ecological damages. On the other hand, rivers are subject to floods. Therefore, determination of risk of<br />river’s bed and right-of-way directly relate to flooding damages and flood management plans.<br />In this paper, a new method for hazard and risk determination of river bed and right-of-way is<br />proposed. The approach is Integrated Flood Management (IFM). IFM not only concerns to river<br />hydraulics and technical issues, but it considers other issues like legal, environment and socioeconomic<br />conditions. This study tries to create a new method for determination of flood risk in the<br />floodplain. We have composed ordinary flood zone mapping (technically using numeric hydraulic<br />models) for Fordo River in Qom province in IRAN. We have also used a Multi Criteria Decision<br />Making (MCDM) approach, which represents IFM aspects to produce another set of flood zoning map<br />by IFM approach. In this procedure, we have benefited from an Analytically Hierarchy Process (AHP)<br />to define land use flood risks. Final map was produced by merging technical map and IFM map.<br />To sum up, new proposed method shows moderate and reasonable zoning instead of hydraulic flood<br />hazard and risk mapping because it uses more criteria for determining the level of flood`s risk in<br />floodplain. Furthermore, this method is more reliable for flood insurance and early flood warning<br />systems or flood damage mitigation, particularly in metropolitan areas.
https://jhyd.iha.ir/article_85493_38848e15e3807966eabc3a89e7de06da.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Risk Analysis Method for Computation of Height of Flood Walls
روش تحلیل ریسک برای محاسبه ارتفاع دیوارهای سیل بند
31
44
85494
10.30482/jhyd.2011.85494
FA
حمید
سنگین آبادی
جلال
عطاری
Journal Article
2011
03
23
One of the structural methods for flood control is construction of levees on the banks of rivers. In<br />traditional design method, the height of floodwall is computed for a fixed design discharge and<br />uncertainties in design flood determination, river hydraulic conveyance and economic analysis are<br />ignored whereas in the risk analysis method effects of these uncertainties are included. In this paper,<br />details of this method were firstly described and then the heights of floodwalls in Qeshlaq River, as a<br />case study, were calculated by application of the risk analysis method. For this purpose, parameters of<br />the load function were calculated by fitting statistical distributions on maximum daily flows and<br />parameters of the wall resistance function were estimated by consideration of uncertainties associated<br />with Manning coefficient, slope of energy line and geometric characteristics of the sections.<br />Furthermore, in economical analysis effects of hydraulic and hydrologic uncertainties were<br />considered. Results showed that application of the traditional method provided underestimated design<br />values and were less reliable compared with the risk-based design method for the floodwalls of<br />Qeshlaq River. In conclusion, application of risk analysis method for design of floodwalls was<br />recommended taking all technical and economical aspects into consideration.
https://jhyd.iha.ir/article_85494_90aa45f180b8e7d1a7812648d4036026.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Numerical Modeling of the Freshwater Lens in Small Islands (Case Study of Kish Island)
مدل سازی عددی لنز آب شیرین در جزایر کوچک (مطالعه موردی جزیره کیش)
45
56
85495
10.30482/jhyd.2011.85495
FA
محمدمهدی
رجبی
حامد
کتابچی
0000-0003-4643-1415
بهزاد
عطائی آشتیانی
Journal Article
2011
03
23
The groundwater system in many small islands consists of a freshwater lens surrounded by seawater.<br />A transition zone exists between the freshwater and the seawater in which relative salinity gradually<br />changes from zero to 100 percent. Saltwater intrusion is the most important hazard to groundwater<br />quality in small islands. Kish Island is one of the few islands in the Persian Gulf with extractable fresh<br />groundwater resources. This paper presents details of a comprehensive study conducted to model<br />seawater intrusion in Kish Island. Three dimensional numerical simulations were carried out using<br />SUTRA a density dependent flow and transport numerical model. Model calibration was performed by<br />Inverse modeling. For this purpose the PEST inverse code was combined with SUTRA. Finally model<br />sensitivity was evaluated for aquifer recharge and permeability. This study shows that SUTRA can be<br />regarded as a valuable tool in saltwater intrusion modeling. This is mainly due to the model`s ability to<br />simultaneously solve flow and solute transport equations, as well as other key features of the model<br />such as its ability to simulate the transition zone and the unsaturated layer above the main aquifer and<br />to model the groundwater system in three dimensions.
https://jhyd.iha.ir/article_85495_45462ff87d6815087d1f03c1e0cccb26.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Mathematical Semi-analytical Model of Combined Flow over Weir and under Gate by Different Geometries
مدلی نیمه تحلیلی برای جریان ترکیبی سرریز- دریچه در شرایط مختلف هندسی
57
67
85496
10.30482/jhyd.2011.85496
FA
جمال
محمد ولی سامانی
استاد گروه سازههای آبی، دانشکده کشاورزی، دانشگاه تربیت مدرس
مهدی
مظاهری
محمدرضا
کدیور
Journal Article
2011
03
23
The most important advantage of applying the combined weir and gate is to maximize its performance<br />under sedimentation conditions. In this paper, a new mathematical model is presented to determine the<br />relationship between stage and discharge for structures consisting of the weirs and gates by different<br />geometries in different flow conditions. Since the geometry of these structures has lateral<br />compression, velocity distribution in transverse section is not uniform. Therefore, the energy and<br />momentum correction coefficients should be used, and in this research, these coefficients are<br />calculated using optimization approach. One great important advantage of this procedure is the use of<br />relatively simple hydraulic principles. To verify the given method, different combinations of weir and<br />gate as a physical model are tested in the laboratory. From the laboratory data it is concluded that the<br />proposed method is capable of calculating stage-discharge relationship by reasonable accuracy.
https://jhyd.iha.ir/article_85496_c044b8dd14fcfad069e0fdb2d2a8725e.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
03
23
Comparison of Turbulence Models for Simulation of flow Around the Submerged Bridge Decks
مقایسه مدل های آشفتگی در شبیه سازی عددی جریان در اطراف عرشه پل های مستغرق
69
85
85497
10.30482/jhyd.2011.85497
FA
مصطفی
حمزه ئی
میترا
جوان
0000-0002-2509-458X
افشین
اقبال زاده
Journal Article
2011
03
23
During a critical river flood event, a bridge deck may become partially or completely submerged by<br />the flow. The deck submergence may be a critical condition for structural stability of river bridges. In<br />this paper, the mean flow fields around a submerged bridge deck and the time averaged drag<br />coefficient on it have been simulated by using FLUENT software. The turbulence models considered<br />are the standard k , renormalization group (RNG) k and Realizable k . In these simulations,<br />the VOF and rigid lid methods have been used for free surface simulation. Reconstruction and Finite<br />volume schemes have been used to determine the position of the free surface in VOF method and the<br />results have been compared. Simulation results of time averaged drag coefficient show that in the case<br />of partially submerged deck, Geometric Reconstruction Scheme in VOF method with standard<br />turbulence model is in better agreement with the experimental results. In the case of fully submerged<br />deck, RNG k and Realizable k turbulence models provide better accuracy than standard<br />turbulence model. Also, simulation results show that Reconstruction based schemes in VOF<br />method are not capable to simulate mixing of water and air and finite volume schemes have to be used<br />for mixing of water and air simulation.
https://jhyd.iha.ir/article_85497_2b520a7b71d80e65ca116a11c31a5c4c.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Annular Aerators in Tunnels with Horse shoe section
هواده های حلقوی در تونل های نعل اسبی
87
100
85498
10.30482/jhyd.2011.85498
FA
محمدجواد
استاد میرزا
امیررضا
زراتی
رضا
روشن
خداداد
صفوی
حامد
سرکرده
Journal Article
2011
03
23
Aeration is one of the most practical and economical methods for prevention of cavitation attack in<br />high speed flows. Many research works are conducted on aerators. Although a general method is not<br />available for aerator design, many aerators are designed and constructed all over the world. Cavitation<br />danger in tunnels also makes the designers to consider aerators for tunnels. Since tunnel sections are<br />usually circular or horse shoe, a specific type of aerator is required for tunnels. Lack of information on<br />application of aerators in tunnels makes some of designers to change the tunnel section to rectangular<br />by subsequent concrete operation and then design the same type of aerators used in spillways. This<br />method is expensive and time consuming. In the present work, annular aerators are studied in a<br />physical model of a tunnel with horse shoe section. The effect of aerator geometry on jet length and<br />spray formation is studied. Experimental results showed that to reduce spray formation, the aerator<br />geometry should follow the tunnel section. It was also concluded that to reduce spray formation in the<br />range of Froude numbers tested, it is better to keep the ramp angle less than 5 degrees. To increase the<br />jet length and efficiency of the aerator, the ramp height should also be increased.
https://jhyd.iha.ir/article_85498_2598588b8fc2eba0e979d50cbdd81e57.pdf
انجمن هیدرولیک ایران
نشریه هیدرولیک
2345-4237
6
2
2011
08
23
Analysis of the Shear Stress on Bed in Bottom Outlet of Dams During Sediment Transportation by Numerical Model
شبیه سازی عددی تاثیر جریان غلیظ بر تنش برشی دیواره تخلیه کننده تحتانی سدها
101
111
85499
10.30482/jhyd.2011.85499
FA
سیدمحمدکاظم
امامی
محمدرضا
کاویانپور
رضا
روشن
Journal Article
2011
03
23
Although water and soil conservation activities reduce reservoir sedimentation, it is inevitable that<br />reservoirs fed by rivers transporting high amounts of sediment will experience sedimentation. The<br />Ghezel-Ozan and Shahroud rivers, which flow into the Sefidroud reservoir dam, are both highly<br />sediment-laden and transport significant amounts of sediment in both forms of bed and suspended load<br />to the reservoir. Hence, it seems that the only practical way to remove the sediment from the reservoir<br />is to flush it out using the chasse method. But it consists of a highly-concentrated water flow of the<br />soil mass move through the bottom outlet that is called a density current. The flow causes significant<br />damages to the boundaries of the conduit by soil erosion and corrosion. In this paper, density current<br />in bottom outlets and its related problems are evaluated and the effects of concentration on wall shear<br />stress are studied. To obtain the requirements for numerical modeling of three phase air-watersediment<br />flow pattern, the model was first calibrated with the experimental measurements of two<br />phase air-water flow taken at Water Research Institute of Iran. Therefore, a numerical model based on<br />multi-phases systems and available theories of numerical models for sediment transport was developed<br />without applying empirical coefficients. Two different concentrations of suspended sediment have<br />been used and the results are compared. The results showed that wall shear stress increases by<br />sediment concentration. For both cases, the shear stress increases up to a maxima after a short distance<br />from the gate. The quantity of these maxims is higher than those measured by flow of pure water.<br />Thus, it is concluded that the sediment flow causes intense shear stress, which is a major threat to the<br />tunnel walls. These damages stimulate the pressure field, which also may trigger cavitations.
https://jhyd.iha.ir/article_85499_3b44207ac876cf318154a3d423a90b77.pdf