Davood Farsadizadeh

• Professor
• Professor at University of Tabriz

Hydraulic jump that frequently occurs downstream of hydraulic structures reduces the excess energy of the incoming flow. This study tested two different heights of discontinuous roughness elements over the horizontal bed and two adverse slopes of -1.5% and -2.5% in the stilling basin. In total, 280 data were collected in laboratory conditions to as...

The Piano Key (PK) weir is a new type of a long crested weir that improves the capacity of discharge through the constant upstream head by increasing the length of the crest. Due to the resulting high discharge capacity of these types of weir, reservoir capacity is increased and dams are stabilised against flooding. The PK weir has been developed b...

One type of long-crested weir is oblique weir. Oblique weirs are longer than standard weirs. Therefore, they can pass more discharge capacity than weirs at the given channel width. The main objective of the present study was to investigate the efficacy of several intelligent models including multiple linear regression (MLR), Gaussian process regres...

In the present study, the flow pressure fluctuations have been measured on the bed of the USBR Type II stilling basin downstream of an Ogee spillway using pressure transducers. The experiments were carried out in a laboratory flume under different flow conditions. In addition, the pressure field in submerged hydraulic jumps was investigated to help...

In this paper, two artificial intelligence (AI) techniques, including Deep Learning (DL) and Multi-Layer Perceptron (MLP), have been applied to predict the pressure fluctuations coefficient (CʹP) along the submerged and free jumps at the bottom of the USBR Type II stilling basin, based on the geometric and hydraulic parameters. This coefficient is...

Weirs are one the most important hydraulic structures for flow control, water measurement and regulating of upstream water elevation in canals, irrigation networks and rivers. For a given of channel width, inclined weirs have longer effective length in comparison with the usual rectangular sharp crested weirs, and this could be effective on their d...

Abstract Cutoff walls play an important role in the stability of various hydraulic structures and dams. Usually, these walls are used upstream and near the heel of the dam in order to reduce the uplift force and in the downstream and close to the toe as the reduction of exit hydraulic gradient. The purpose of this study was to investigate the effe...

The Piano Key (PK) weir is a new type of long crested weirs. This study was involved the addition of a gate to PK weir inlet keys. It was conducted by the Department of Water Engineering, University of Tabriz, Iran to determine if the gate increased hydraulic performance. A Gated Piano Key (GPK) weir was constructed and tested for discharge ranges...

Scouring downstream of grade control structure is a common problem. W-weir structures are recommended for controlling, reducing soil erosion, and development aquatic organisms habitat. W-weir structures can provide energy dissipation, increased aquatic habitat, grade-control, and bank and bed stabilization through the diversion of conveyance with t...

Scouring downstream of grade control structure is a common problem. W-weir structures are recommended for controlling, reducing soil erosion, and development aquatic organisms habitat. W-weir structures can provide energy dissipation, increased aquatic habitat, grade-control, and bank and bed stabilization through the diversion of conveyance with t...

A free-surface vortex is a mass of water rotating around an axis perpendicular to the free surface. It can occur when withdrawing water from reservoirs or rivers at hydropower intakes with low submergence. Existing vortex models provide general information about the symmetric vortex structure. The vortex structure occurring in an approach flow at t...

Shock wave formation is very important in studies of supercritical flow. Based on increasing water height more than inlet flow depth, spreading over a wide range of downstream channel and making disturbances in water surface, formation and propagation of these waves are unfavorable in engineering. The present paper is an attempt to study the superc...

Investigation of Sedimentation Patterns Downstream of U-weir in a Sinusoidal Mild Bend

Studies on the relationship between plant nitrogen content and soil nitrogen reduction under elevated CO2 conditions and with different nitrogen additions in wetland ecosystems are lacking. This study was meant to assess the effects of elevated CO2 concentrations and inorganic nitrogen additions on soil and plant nitrogen cycling. A cultured ripari...

The paper presents the results of an experimental study carried out to investigate the effect of geometric and hydraulic parameters on energy dissipation and location of the hydraulic jump, with a change in the height of roughness elements and the divergence of walls in different discharges. Experiments were conducted in a horizontal rectangular ba...

Erosion in river bends causes loss of agricultural lands, adjacent facilities, and fish habitat. W-weir structures are recommended for controlling and reducing soil erosion as well as developing habitat for fish and other aquatic organisms. This paper presents the results of an experimental study carried out to investigate the effect of a W-weir st...

Hydraulic jump is an extremely turbulent flow which implies the development of large-scale turbulence and energy dissipation. In the present study the characteristics of hydraulic jump, including sequent depth, relative length of the jump, and energy loss on rough bed with discontinuous roughness elements of lozenge shape over adverse slope have be...

Experimental Study of the Effect of the W-Weir Height on Reduction of Scour in a Sinusoidal Mild Bend

Flow Separation in the upstream of the intake channel is a critical issue causing eddy flow into the intake entrance. It can both reduces intake efficiency and the effective width of flow and increases sediment deposition in the intake entrance. Therefore, it is essential to identify dimensions of flow separation zone. Installation of submerged van...

Flow Separation in the upstream of the intake channel is a problem which produces an eddy flow at the intake entrance. It reduces the intake efficiency and the effective width of flow in intake. Therefore, it is essential to identify the dimensions of the flow separation zone. Installation of submerged vanes in intake entrance is a method which has...

Technical note

Density currents are formed when gravity acts upon a density difference between two different fluids, and the driving force is the buoyancy force. These currents are the most important transport mechanisms and deposition of noncohesive sediments in narrow and deep reservoirs. In this research, 126 experiments were performed to investigate the effec...

The designed length of the rectangular side weirs sometimes becomes too long that makes it non-practical from the engineering point of view. In order to decrease the length of channel opening with the desired water height, this study focuses on applying trapezoidal geometry for side weirs. The discharge coefficient needs to be found experimentally...

Formation of the vortex at the dams creates the air entrainment to the intakes and reduces the dewatering capacity of the system (in case of insufficient submergence of the intake). One of the common methods to preventing the air entrance and reducing the power of the vortex is the using of the meshed plates. Because of the researches on the using...

Investigation of the size of the slot on the Semi-Cylinder Structure on Pressurized Flushing of Reservoirs

The effect of different types of surface roughness on a turbulent boundary layer was studied using 1D velocity measurements in a relatively high Reynolds flow. The roughness consisted of trapezoidal ribs with horizontal spacing and roughness height k . The roughness elements were aligned in a direction transverse to the flow. A series of 7 tests of...

Undular flow above the broad-crested weirs is an open channel flow phenomenon which occurs under certain hydraulic conditions. The flow surface on the weir transforms to sinusoidal waves and the number of waves may vary from one to over 10. Hence weir cannot be utilized to measure the flow discharge due to the formation of surface undulations above...

Artificial neural networks (ANNs) and genetic programming (GP) have recently been used for the estimation of hydraulic data. In this study, they were used as alternative tools to estimate the characteristics of hydraulic jumps, such as the free surface location and energy dissipation. The dimensionless hydraulic parameters, including jump depth, ju...

In this study with creating a gap in the lower part of the semi-cylinder which is employed in front of a bottom outlet, the effect of this semi-cylinder in flushing capacity was studied. The results indicated that the flushing cone in plan was the approximately semi-cylinder shape. Using semi-cylinder with the diameter of 2.5 times greater than the...

Stepped spillways have significant importance for their indisputable effect on energy dissipation and for compatibility with roller compact concrete method in construction. In order to design these spillways, physical models are commonly used in spite of spending great time and cost. Progress of high speed computers, however, permits to utilize com...

In this study, trends of evaporation in the northwest region of Iran are evaluated for 15 stations which have 30 years of evaporation records. The trends are detected using three variation of ManKendall (MK) test. These variations include (1) Man-Kendall without autocorrelation (2) Man-Kendall with lag-1 autocorrelation and trend free-pre-whitening...

Estimation of air temperature is one of the important problems in agricultural planning also in water resources management which can be done by using different empirical, semi-empirical and intelligent methods. In the present study, Adaptive Neuro Fuzzy Inference System, artificial neural networks and genetic programming are used to estimate maximu...

Application of a horizontal drain in an embankment dam has been a prevalent method to lower the phreatic line and dissipate the excessive pore water pressure. The efficiency of this type of drain is often attributed to its length, while the effect of thickness is ignored. In this research, a series of tests were accomplished and different drain siz...

Behavior recognition of scour hole dimensions at abutment, their time variation and the determination of equilibrium scour depth in designing and applying abutments are very important so that variation of scour hole dimensions and their way of development can have significant effects on the scour mechanism and the created scour hole development. In...

The application pattern for single, stationary spray sprinklers exposed to the wind was modelled to simulate water application in a centre pivot-irrigated field. In the model, a dynamic square grid of cells for water application and a static square grid of cells for water collection were defined. The dynamic grid contained the information on the wa...

In water construction projects, river engineering, and irrigation and drainage engineering, it is vital to estimate the accurate volume of the sediment transported by rivers. As the sediment transport phenomenon is an immensely complex problem, therefore presenting an appropriate solution for precise evaluation of the suspended load in rivers is te...

Hydraulic jump characteristics were studied experimentally over six corrugated beds with varying wave steepness, which had corrugation and Froude numbers in the range of 0.286–0.625 and 3.8–8.6, respectively. The effects of wave height and length of corrugation on the basic jump characteristics, including free surface location, velocity, shear stre...

Hydraulic jumps have been used for dissipation of kinetic energy downstream of hydraulic structures, such as spillways, chutes, and gates. It was found that if jumps were made to occur on corrugated beds, tail water and length of jumps reduced significantly. During the formation of the hydraulic jump on a corrugated bed, the flow is turbulent water...