انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 Investigation of Effective Parameters on the Hydrofoil Performance near the Free Surface of Water بررسی پارامترهای موثر بر عملکرد هیدروفویل در نزدیکی سطح آب 1 17 85405 10.30482/jhyd.2012.85405 FA محمدحسن جوارشکیان علی اسماعیلی Journal Article 2011 03 21 In this study, a numerical method is used to assess the effect of thickness, camber, submergence depth and flow velocity around a submerged hydrofoil. A pressure based algorithm is used to solve Navierstokes equations, and Volume of Fluid (VOF) approach is applied to simulate two-phase fluid (water and air). The model and second order upwind scheme have been used for turbulence models and differential schemes, respectively. For verifying, a part of results is compared with published experimental results. The numerical and experimental results show excellent agreement; thus, the process of numerical simulations is confirmed. The results of this study illustrate that the lift and drag coefficients increase with rising the thickness of the hydrofoil, but the lift to drag ratio has a downward trend. On the other hand, the lift and drag coefficients increase with growing the camber of the hydrofoil, but lift to drag ratio has upward trend. Therefore, to opt the best section of the hydrofoil, the less thickness and the high camber are more desirable to getting high hydrodynamic performance. The switched of the hydrofoil section obviously affects the airflow and boundary layer formed on the free surface of water. Moreover, lift and drag coefficients become high by increasing the submergence depth and angle of attack, as a result lift to drag ratio increases. Lift and drag coefficients are decreased by increasing flow velocity, and lift to drag ratio has a downward trend. https://jhyd.iha.ir/article_85405_af0a19cbbf7ec9e02e05bfa2e227ba21.pdf

انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 Coupled Analysis of Fluid Transients and Structural Dynamic Responses in Pipelines by MOC-FDM تحلیل همزمان جریان غیرماندگار و پاسخ های دینامیکی سازه خطوط لوله به روش MOC-FDM 19 31 85406 10.30482/jhyd.2012.85406 FA سید محمود جزایری مقدس دانشگاه شهید چمران حسین محمدولی سامانی Journal Article 2011 03 21 Water hammer is a type of transient flow in pipelines which may in general be produced due to valve closure or sudden shut down of pumps. Transient flow creates sudden variation in the velocity and pressure of fluid flow in the pipelines which in effect may induce some dynamic vibrations in the structure of pipe. Furthermore, such structural vibrations can affect the fluid flow. Taking into account them is necessary for modeling of fluid-structure interaction. In this paper the fluid-structural interaction (FSI) of water hammer in pipeline systems are investigated. Two sets of hydraulic and structural equations with common variables have been numerically analyzed through MOC-FDM simultaneous solving process which has been prepared by a computer-assisted program. Some examples have been solved by this method, with satisfactory results. This indicates that fluid-structure interaction can have critical effect on the value of fluid pressure. https://jhyd.iha.ir/article_85406_a9f9a8a150d14a59a3cdaa03337a1360.pdf

انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 The Effect of Wastewater on the Non-Settling Velocity and Shear Stress of Cohesive Sediments تاثیر پساب شهری بر سرعت و تنش برشی غیررسوبگذار رسوبهای چسبنده 33 42 85407 10.30482/jhyd.2012.85407 FA میلاد خواستار بروجنی حسین صمدی بروجنی عضو هیات علمی دانشگاه شهرکرد کاظم اسماعیلی 0000-0001-5354-0949 Journal Article 2011 03 21 Sedimentation in open channels is one of the basic problems in the management of irrigation networks. Complexity of behavior of cohesive sediment transport makes determination of the criteria for open channel design to be difficult. The purpose of this study is to determine non-settling velocity and non-settling shear stress for open channel flow containing wastewater and suspended cohesive sediment. Experiments were carried out in an annular flume located in the hydraulic laboratory of Shahrekord University, Iran. The sediment samples were taken from Pirbalut dam reservoir, located upstream of Northern Karun basin. The result showed that wastewater content in flow causes the suspended sediment deposition and flocculation to be likely increased. It also caused the threshold of non-settling velocity to be increased at a rate of 10% compared to pure water. A similar result was also obtained for threshold of shear stress. The results obtained from this study were compared and the results showed that the empirical methods were not capable in calculating non-settling velocity for open channel flow containing waste water and suspended cohesive sediments. The results also showed that the Froud number should be more than 0.47 for non-settling condition of suspended cohesive sediments. https://jhyd.iha.ir/article_85407_62e5bd018861ec37550bc5239a60133a.pdf

انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 Development of a Numerical Model for Predicting Dynamic Pressures in Open Channel Flow using Non-Orthogonal Curvilinear Coordinate Grid توسعه مدل عددی برای پیش بینی فشارهای دینامیک در جریان کانال های باز با شبکه منحنی الخط غیرمتعامد 43 58 85408 10.30482/jhyd.2012.85408 FA زهره دهقان بهابادی محمدرضا هادیان امیررضا زراتی Journal Article 2011 03 21 A 2DV numerical model is developed for solving unsteady Navier-Stokes equations with the ability for calculating dynamic pressures in non-orthogonal curvilinear coordinate grids for free surface flows. The model is based on fractional step method (or projection method). The free surface elevation is calculated using continuity equation. The present method uses the advantages of shallow water models for calculating free surface elevation (even in cases with large changes) and benefits the flexibility of moving non-orthogonal grids. Moreover, this method presents the ability of developing a shallow water solver to take into account the dynamic pressures. The simulation of water elevation in a gradually varied flow, showed the ability of mesh adaption in moving and curved boundaries. Comparing the results of the model with experimental data and other numerical models, for flow passing over a hump and trench, confirms the ability of the developed model for simulating the free surface flows. Having the ability of calculating free surface and dynamic pressures, the model can therefore be applied to rapidly varied flows. https://jhyd.iha.ir/article_85408_8e1853b6a873a42959e1b8a70e9dc702.pdf

انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 Armoring Effect on Local Scouring around the Bridge Pier under (Part1 :) Steady Flow مطالعه تاثیر لایه سپری بر آب شستگی پایه پل، تحت اثر جریان دائمی (بخش یکم) 59 75 85409 10.30482/jhyd.2012.85409 FA عبدالرضا کبیری سامانی دانشیار، دانشکده مهندسی عمران، دانشگاه صنعتی اصفهان 0000-0002-5984-3892 Journal Article 2011 03 21 In this study armoring effect on local scouring around bridge pier under steady flow condition was investigated based on model experimentation. Different combinations of bed-armor layers were employed. Three circular piers of 22, 33 and 42 mm were used. Results show that while small bed particles are under the protective effect of armor layer, increasing the total scouring depth, yields an increase in the secondary armor layer depth until the armor layer itself is not influenced by the horseshoe vortices. The minimum stabilized secondary armor layer is identical to the armor grain size. Results showed that there is not meaningful correlation between total scouring depth and B/d (where B is the pier diameter and d is the mean bed grain sizes) for B=33 and 42 mm. However for B=22 mm, increasing B/d tends to increase the total scouring depth. For the armor layer particles size of 2.36 mm the armoring effect for B=22 mm is vanished. The most important parameters in evolution of scouring depth are the armor layer grain size and the armor layer thickness. https://jhyd.iha.ir/article_85409_f0f915de822b7ed9230c5c4a7998210b.pdf

انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 4 2012 01 21 Study of Dynamic Pressure Distribution over the Bed of Compound Flip Buckets مطالعه توزیع فشار دینامیکی بر روی بستر پرتاب کننده جامی مرکب 77 90 85410 10.30482/jhyd.2012.85410 FA امید امین الرعایایی یمینی محمدرضا کاویانپور Journal Article 2011 03 21 Flip buckets are usually placed at the end of chute spillways or outlet conduits of high dams. The projected jets from these buckets jump into plunge pools to dissipate the destructive energy of plunging jets. Compound flip bucket is a special bucket with a non-zero degree of cross sectional slope, followed by a curvature in its longitudinal direction. These structures are very suitable for restricted geometries and conditional topographies. Although, studies of flow over flip buckets started many years ago and valuable information is available for similar buckets, still there are uncertainties regarding the flow over compound flip buckets. Therefore, in this study the hydraulic parameters such as pressure, velocity and depth of flow on these structures were evaluated. Two chute spillways with their flip buckets were used to check the pressure distribution and its variation with different hydraulic characteristic along the compound flip buckets. The scaled model of Gotvand dam (south of Iran) at Water Research Institute of Iran was used for this study. The Froude number varies in the range of 3.5 to 7.5. The results are presented in the form of dimensionless equations, which are calibrated based on the present results. The location of maximum dynamic pressure on the bed of the compound flip bucket is also determined. https://jhyd.iha.ir/article_85410_0f26f3dbc43ed58b11ca7e90f40acea7.pdf