Ahmed Y Mohammed

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• Professor (Full) in hydraulic engineering at University of Mosul

The behavior of free surface flow on a rectangular free over fall which has a triangular shape is studied experimentally to obtain water surface profile (WSP) and the relation between brink depth and critical depth. A series of experiments were conducted in a rectangular laboratory flume, with two shapes of crest and three angles of inclination. Th...

In this paper, the inclined side weir discharge coefficient was studied using a side weir with three different crest angles (θ=4°,8°,12°) fixed either against and in the flow direction, and the results are compared with those from a horizontal side weir crest (θ=0°). In total there were seven models. The results show that the De Marchi assumption...

A free overfall at the end of the channel is used as a flow measuring device. In this paper, theoretical end depth ratio (EDR) and end depth discharge (EDD) relationships have been studied and obtained for subcritical flow in a rectangular channel with a free overfall and with different end lip shapes; i.e., triangular and skewed lip. For all model...

In thepresentworkthealternativeconceptofanelementarydischargecoefficientalong the longitudinalsideweirwasstudiedusinganobliqueweir.Fivedifferentangles(30o, 45o, 60o, 75o, and 90o) intheflowdirection(inclinedtotheleft)withrespecttothebranchchannelwallwere examined. Anumericalsolutionoftwoordinarydifferentialequationswasproposedfordischarge and flowd...

The present study focuses concept for an elementary discharge coefficient that is related to the discharge flowing through an elementary strip along the side weir length. Simulations of discharge and water depth elevation were done. It is shown that the predicted discharge was agreement with the observed one within an error not exceed 10%. A discha...

The beam-column joint is a critical structural element in reinforced concrete structures, especially under lateral loading conditions. These joints are prone to failure due to high shear stress concentrations, making their accurate design and assessment essential for structural safety.This study aims to assess the accuracy of existing building code...

Hydraulic jumps are critical phenomena in hydraulic engineering, observed in open channels, rivers, and coastal areas. This study investigates the characteristics of hydraulic jumps formed downstream of stepped cylindrical weirs. A total of 27 physical models of stepped cylindrical weirs were constructed, varying weir heights (P = 30, 45 and 60) cm...

Local scour occurring downstream hydraulic structures is one of the most common problems affecting the safety and stability of the structure. The present laboratory study was conducted to reduce the size of the hole pit using 12 models of cylindrical and stepped weirs with a fixed height (p=30 cm) and a single slope angle (θ=45°) and using apron of...

A spillway is an essential hydraulic structure that discharges excessive water, especially during floods from upstream to downstream of the dam. A shaft spillway is sometimes used when a limited area is available. This study used four physical models of vertical shaft spillways with different edge shapes to study the flow characteristics. Each cas...

This study investigates the discharge coefficient (Cd) of labyrinth sluice gates, a modern gate design with complex flow characteristics. To accurately estimate Cd, regression techniques (linear regression and stepwise polynomial regression) and machine learning methods (gene expression programming (GEP), decision table, KStar, and M5Prime) were em...

Two hundred experiments were conducted on triangular cross-section gates, folded in one and two-cycle modes, with varying apex angles and opening heights under different upstream flow conditions. The results were analyzed and compared with standard gates under identical hydraulic conditions. The hydraulic performance of the proposed models was then...

This study uses machine learning (ML) to predict the end-depth structure’s discharge and critical depth (yc). Linear regression, M5P, random forest, random tree, reduced error pruning tree, and Gaussian process (GP) are the ML methods used in this investigation. The findings indicate that the radial kernel function-based GP model is most suitable c...

Weirs are among the most essential hydraulic structures for measuring water discharge in open channels. The prediction of water discharge over weirs should be as precise and straightforward measured as feasible. The experimental investigation of flow prediction over varied heights of a conventional rectangular sharp-crested weir was conducted in th...

Water is one of the natural resources that man has known since ancient times and relied on daily. Its availability is an urgent necessity to sustain life and achieve human development. It is the primary food source for many people who live near the river and depend on fishing and agriculture for their livelihood. Therefore, dams are built across ri...

The spillway is a hydraulic facility that drains excess water or in flood by transferring it from the reservoir at the inlet of the dam to the outlet. It is considered a safety element for the dam. The type of spillway depends on several factors, including the type of dam, the topographical geological nature of the ground, the highest discharge, an...

Free overfalls are hydraulic structures used in flood control, water supply, irrigation, and flow measurements. The hydraulic systems of free overfall depend on rectangular end shape. The studies that dealt with triangular crest are few and almost non-existent. In this study, a triangular end-shape design uses multiple linear regression (MLR) and g...

Some hydraulic structures and phenomena, including compound channels, must be studied in relation to open channel flow. Despite the fact that the primary channel and watersheds share a similar degree of roughness, estimating discharge in composite channels with mainstreams and flood plains has proved tricky. The flow discharge for a compound channe...

Weirs are hydraulic obstructions constructed across an open-channel flow causing a rise in water which is useful to convert water to the channels upstream as well as using these structures as a measuring device. There are different types, and a sharp-crested weir is one of them. Local scour downstream hydraulic structures are one of the most critic...

The hydraulic structures are one of the important constructions needed in open channel flow to control the water level, one of these hydraulic structures is the sluice gate, which is needed for flow diversion as well as a measurement device in the irrigational channel. Many studies that dealt with gate hydraulic properties and energy dissipation do...

Water is one of the natural resources that man has known since ancient times and relied on daily. Its availability is an urgent necessity to sustain life and achieve human development. It is the prima food source for many people who live near the river and depend on fishing and agriculture for their livelihood. Therefore, dams are built across rive...

A spillway is a hydraulic structure that discharges excessive water, or in cases of flood, by transferring it from the reservoir upstream to downstream of the dam; it is considered a safety element for the dam. A shaft spillway is used in cases where there are not enough spaces to create another type of spillway. In this study, 12 physical models o...

Hydraulic structures such as sluice gates are more sensible of driftwood that is transported by a river; all this debris, like a trunk, deadwood, and rootstocks, can be accumulated upstream hydraulic structures may cause many hydraulic troubles, so studded such as these phenomena more essential to prevent or reduce its effects on these structures....

The hydraulic structures are one of the important constructions needed in open channel flow to control the water level, one of these hydraulic structures is the sluice gate, which is needed for flow diversion as well as a measurement device in the irrigational channel. Many studies that dealt with gate hydraulic properties and energy dissipation do...

More than eighty years ago, De-Marchi indicated an assumption for hydraulics of flow-through side weir. Many researchers who study side weir depended on this assumption in their studies. Many studies for side weir were carried out in different channels, and numerical studies supported the results. This study deal with a comprehensive review of disc...

Several studies indicate that using hydraulic structures results in some adverse effects that affect the stability of these structures, including scouring the floor. Many researchers resorted to using defensive means to reduce the flow's speed and energy as much as possible. One of these means is the use of screen walls. Therefore, the current stud...

The great economic importance of increasing the energy dissipation flow rate in stepped weirs prompted researchers to make several changes to the geometrical shape. In this study, (36) physical models were constructed to compare cylindrical stepped weirs with traditional weirs. (27) Models of cylindrical stepped weirs and (9) traditional stepped we...

The great economic importance of increasing the rate of energy dissipation of flow for its contribution to reducing the dimensions of the stilling basins and thus reducing the cost of construction prompted researchers to make several changes to the geometrical shape of the weirs in order to improve the percentage of dissipation energy of the flow....

The hydraulic structures are one of the important constructions needed in open channel flow to control the water level, one of these hydraulic structures is the sluice gate, which is needed for flow diversion as well as a measurement device in the irrigational channel. Many studies that dealt with gate hydraulic properties and energy dissipation do...

The characteristics of the flow in the vertical spillway were studied in this research using dual water jets as a hydraulic and economical tool (way) for improving the performance of the vertical spillway by increasing the amount of discharge passing through the vertical spillway, increasing the discharge coefficient and raising the value of the Fr...

The water intakes is one of the important hydraulic installations that is built with the dam and is used to control the water level in the dam's lake. The vertical spillway is a type of intakes used in dams to control floods and as a intakes to change the stream the river in mountainous areas specially. One of the most important problems that occur...

In this paper, four gate openings and fifteen operating scenarios in terms of the difference in the arrangement of working gates were studied. The Expansion Ratio (e) which is (the ratio of the total width of the channel to the total width of the working gates) was calculated for each scenario. It can be seen that when the value of (e) was the larg...

Flow-through a bridge opening may run either partially or fully. In this research, backwater rise, hydraulic loss coefficient, and drag coefficient for two bridge models and three flow conditions are investigated. Based on the dimensional analysis theory, an equation was developed to calculate the water level difference Δh between the upstream and...

Flow-through a bridge opening may run either partially or fully. In this research, backwater rise, hydraulic loss coefficient, and drag coefficient for two bridge models and three flow conditions are investigated. Based on the dimensional analysis theory, an equation was developed to calculate the water level difference Δh between the upstream and...

Abstract In this study, the hydraulic properties of flow for a Multi-open vertical sluice gate were studied in two directions, the first one is studying energy dissipation and the second one is studying hydraulic properties. The first direction includes study the flow from the gates in its two states, supercritical flow (before the hydraulic jump)...

In irrigation and drainage structures, side weir is widely used for flow diversion from main to branch channels. Side weir is also used as a measuring device for discharge measurements, so discharge coefficient was mainly studied in many previous studies. Skew side weir was not taking a good highlight in previous studies and literature, so the pres...

Side weir is a hydraulic structure, which is used in irrigation systems to divert some water from main to side channel. It is installed at the entrance of the side channel to control and measure passing water into the side channel. Many studies provided side weir water surface profile and coefficient of discharge to measure water discharge diverted...

Hydraulic jump can be defined as a sudden change or rise of water level because of changing the channel slope from steep to mild combined turbulent flow. This can be used for energy dissipation to reduce flow energy downstream hydraulic structure. Recent studies dealt with energy dissipation downstream hydraulic structures such as stepped weir by c...

In this paper the effect of vortex formation upstream inclined sluice gate, discharge coefficient as well as predicted discharge equation have been studied for several gate openings (3,4&4.5) cm, five discharges and three different gate cases, vertical and inclined opposite flow direction in (30 and 45)° angles. It was found that there is no vortex...

In this paper, the relation between the brink and critical depth is studied experimentally and theoretically to predicted theoretical discharge equations using in rough free overfall. Three different; bed rough materials, sizes and distributions were used and tested experimentally to develop the discharge relationship. An equation is proposed to de...

In this paper a feed-forward back-propagation type of neural network as well as the multi nonlinear regression model using statistical programming were used to determine the critical depth and discharge passing over the enddepth model, free overfall. This was achieved by training and validating (215) experimental data. The results of the trained ve...

In this paper, the free overfall in rectangular channel with a different slopes and bed rough distribution was studied. Bed roughness was made of wood allocated in three different cases: two, three and zigzag rows. The aim of this study is to obtain discharge equations for free overfall depending on brink depth and slope. Three empirical equatio...

This paper present the effect of the lower gate lip on the coefficient of contraction, velocity and discharge which have been made in a rectangular flume with four gates opening from (2 to 4.5) cm, five different discharges from (6.2 to 18.15) l/s and five different gate cases (vertical and inclined vertically) by angle (45)° with and opposite flow...

water resources and climat changes

In this study the effect of the lower gate edge on the water surface profile (W.S.P) have been studied in a rectangular flume with four gate openings (2, 3, 4 and 4.5) cm, five upstream of water heads (18.9,21,24,26 and 28.9) cm and five gate cases (vertical and inclined vertically by angle 45º with and opposite to flow direction) with horizontal a...

In this study highlights the possibility of increasing the discharge of side channel using inclined side weir with different crest height upstream of flow, five models were used and flow profile were studied along the side weir. Devised an equation to calculate the coefficient of discharge for the rectangular sharp crested weir, and used for calcul...

The properties of a hydraulic jump and energy dissipation downstream sluice gate have been studied Three gate opening 2, 3, 4 cm were used to carry out the experiments in a rectangular channel. It was found that energy dissipation through the hydraulic jump is a function of Froud, Weber numbers and gate openings, and that energy dissipation decreas...

The experiments where made in hydraulic laboratory, water resources Dept., Mosul University, Iraq. In this paper the effect of bed roughness for free overfall on flow characteristics in open channel are studied. The characteristics include, water depth over free overfall, critical and brink depth at lip of free overfall. The aim of the study is to...

This paper studies the performance of side weirs by changing the end lip slope of this weir using three angles (00,30,60) opposite flow direction, depending on Froude number and slope of side weir end lip, an equation for the coefficient of discharge for the side weir has been defined. From the results it was found that the side weir inclined (30)...

This paper present the variation between brink and critical depths for free overfall, of water over two models of broad crested weirs with different edge, straight vertical and skewed with an angle (30)o. The discharge was measured for the two models and compared with calculated one observed from theoretical equation. The results showed that the ca...

climate change

water resources