Department of Hydraulic Structures (1989 - Present)
Hydraulics
Civil Engineering, Liverpool, Liverpool, England
Hydraulics
Civil Engineering, Newcastle, Newcastle, England
Structural Engineering
Structural Engineering, Sharif University of Technology, Tehran, Iran
Structural Engineering
Structural Engineering, Sharif University of Technology, Tehran, Iran
Structural Engineering
Structural Engineering, Sharif University of Technology, Tehran, Iran
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Submerged vanes are installed in waterways bed. These structures are usually used in groups and their main performance is to create an eddy current which leads to change in stream flow pattern and the bed topography in waterways. Performance of submerged vanes group depends on their arrangement and size. In this study using SSIIM numerical model, hydrodynamic analysis of flow pattern and bed topography around a single submerged vane in a straight channel was done and tried to estimate proper arrangement of submerged vanes group. The geometry of arrangement consisted of longitudinal distance between consecutive vanes, transverse distance of two adjacent vanes, and transverse distance of submerged vanes from the outer wall. Therefore, after v
Severe urban floods have frequently caused social and financial infrastructure problems due to a lack of hydraulic capacity of urban drainage systems or the structural failure of network elements. Conventional, reliability-based design methods of drainage networks only provide acceptable performance under expected conditions of loading. In this study, a new approach based on resilience is proposed for the rehabilitation of urban drainage systems; this approach is able to maintain a predefined service level under both external and unexpected internal loads, including different scenarios of blockage and a severe rainfall event. The performance of different design methods: resilient, non-resilient, deterministic and uncertain models, is compre
The present study investigates the physics of the flow and the role of coherent structures of flow in the scouring process, around a vertical dike, located in a straight channel, at the beginning of scouring process (flat bed). Therefore large eddy simulation (LES) method is applied for a flow with a relatively low Reynolds number (Re= 18000). The inflow is thoroughly turbulent and full of realistic turbulent fluctuations. After visualizing the flow, it was found that the intensity of the primary horseshoe vortex (HV) is largest at vertical sections around the tip of the dike. In this region, the core of the horseshoe vortex fluctuated between two modes. In one of them (zero-flow mode) the horseshoe vortex gets closer to the dike and the be
Introduction: Sediment transport is one of the most basic and important characteristics in river hydraulics and bed morphology. The prediction of sediment transport path in rivers and also artificial laboratory channels is absolutely complicated, and mostly conducted with semi-empirical methods. In such cases, the Lagrangian method is essential for exploring the physics of individual sediment particles. The investigation of the flow pattern in the compound channels originated from 1960s and followed by the exploration of turbulence structures of overbank flows. However, studies on the characteristics and processes of sediment transport in the compound channels are rarely conducted. For completion this gap, in this experimental study, the ro
Submerged vanes are installed in waterways bed. These structures are usually used in groups and their main performance is to create an eddy current which leads to change in stream flow pattern and the bed topography in waterways. Performance of submerged vanes group depends on their arrangement and size.In this study hydrodynamic analysis of flow pattern and bed topography around a submerged vane in a straight channel was done andtried to estimate proper arrangement of submerged vanes group. The geometry of arrangement consisted oflongitudinal distance between consecutive vanes, transverse distance of two adjacent vanes, transverse distance of submerged vanes from the outer wall.
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The fuse plug is used as a safety valve to protect the dam from catastrophic failurs caused by overtopping flow. In this experimental study, using a series of experimental tests, the effect of plug fuse washout on the outflow discharge from the dam reservoir due to change the width and depth of the pilot channel has been investigated. The important point in this study is to be kept constant water level during the overtopping flow and the failure of the structure for the more similarity of this process to reality. The results of this experimental study are the outflow hydrograph resulting from the overtopping flow the change in width and depth of the pilot channel. Also, the effect of changes in the outflow discharge more dependent on the de
Study of open-channel turbulent flow over rough bed is beneficial to provide a better understanding of many riverine physical processes. Indeed, the knowledge of rough bed turbulent flow has a significant effect on sustainable environmental management of the mountainous rivers. The structure of rough bed turbulent boundary layer in inner region is affected by bed geometry in addition to flow characteristics (eg viscosity). Presence of rough elements in the channel bottom makes differences between boundary layer flow over the smooth and rough beds. Presence of roughness enhances the secondary currents. The secondary currents’ enhancement can play an important role in sediments’ transversal and longitudinal transport. The secondary curren
It is well known that the shortage of water is one of the most serious problems that faces the mankind. Therefore the study and search for the phenomenon that have impact on the water reservoirs and other natural resources of water, is essential. One of the most fundamental phenomenons relating to water reservoirs is the density currents. The importance of the investigation and analysis of the hydraulic behavior of density currents will be apparent when we consider the consequences of the occurrence of these currents and its effects on the erosion of water reservoirs and also the sediments that they cause to be deposited in these reservoirs. For example the incoming of these currents in water reservoirs will effect the biological activities
In this study, a numerical 3D model for simulation of lateral intake from the main channel with trapezoidal section has been developed. This model has solved the 3D Reynolds equations using finite volume method and k-ω turbulent model for solution of turbulent equations. The equations discretized at non-orthogonal and non-staggered curvilinear mesh. Given the lack of mesh orthogonally, it is necessary to enter a new item for modification of pressure equations.? Also, power-law scheme and the SIMPLE algorithm have been used for parameter’s discretization and pressure-velocity coupling respectively. Developed model verified by simulating of complex flow pattern at lateral intake from a straight channel and a proper fitness between laborato
Intake structures which are used as water diverting structures in open channels, rivers, and reservoirs are of the oldest issues of hydraulic engineering. In this study, a lateral pipe intake was proposed as a flow diversion structure provided in side walls of a channel, and its discharge characteristics and flow pattern was studied numerically using 3D CFD package, Flow-3D. The simulations have been performed for various parameters. The results showed that the lateral pipe intake with 90o angle has the highest efficiency among all of our simulation scenarios. The vortex and the separation zone in the lateral pipe intake were formed behind the pipe. Also, formation of the recirculation zone behind the lateral pipe intake can be affected by
Lateral intake is a hydraulic structure which is broadly used for purposes such as agricultural consumption or urban water supply. To improve the efficiency of this structure, it is common to install a submerged vane near the entrance of this structure. Despite common applications of this structure, there is still a lack on correct description of flow structure near this structure and the variability of flow characteristics due to the geometrical characteristics such as lateral intake angle. In present study, we numerically investigate the role of submerged vane and lateral intake angle on flow structure using FLOW-3D simulation package. The results show that the lateral intake with 45? angle has the highest efficiency which ca
An accurate model for the estimation of the drag coefficient of a falling sphere is essential for different theoretical analyses and engineering applications (Barati et al. 2014c). Ram?rez (2017) summarized relationships of the frictional drag coefficient and presented the historical chronological sequence of the coefficient. While the author’s intention is laudable, this note discuss some important issues in the subject matter.The first issue is that Ram?rez (2017) classified new strategies for obtaining relationships between sphere drag coefficient, f, and particle Reynolds number, Re, in two categories:(a) matched asymptotic expansions and (b) curve-fitting schemes. However, one of the most recent approaches is the high-resolution nume
The saltation regime is very important for understanding the sediment transport mechanism. However, there is no consensus on a model for the saltation regime. This study answers several questions raised with respect to the Eulerian–Lagrangian modeling of sediment transport. The first question is why the previous saltation models that use different combinations of hydrodynamic forces yielded acceptable results? The second question is which shear lift model (i.e. a shear lift expression and its coefficient) is more appropriate? Another important question is which hydrodynamic forces have greater contributions to the saltation characteristics of a sediment particle? The last question is what are the contributions of the turbulence fluctuatio
Urban floods may cause a wide range of undesirable consequences in populated areas when drainage networks do not have enough capacity or encounter unexpected loads such as blockage. Although both external loads (like heavy rainfalls) and internal factors such as structural failure/blockage of different parts of networks play an important role on urban inundation, most of the implemented design approaches only consider effects of external loads on Urban Stormwater Drainage Systems (USDSs). In this study, a new resilient and stochastic approach is developed by connecting a multi objective optimization algorithm to a numerical solver/meta-model within a Copula-based Monte-Carlo framework in order to design/rehabilitate of USDSs considering the
One of the usual and useful techniques for the flow field measurement in open channels is Acoustic Doppler Velocimeter (ADV). Physical presence of ADV probe and its holding system against flow disturb natural flow pattern which can change turbulent flow structure. Thus, the error of the Acoustic Doppler Velocimeter is consist of its intrinsic error and the physical presence of ADV against flow. To study this issue in this paper, flow field in an open-channel is measured using Particle Image Velocimetry (PIV) technique and side-looking ADV probe. The results show that sreamwise velocity obtained from both methods are in good agreement and on average, there is 5 percent difference, while vertical and lateral components of velocity are conside
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