Mohammad Akram Saadi -

Gender	MALE
Place of Work	Mosul Technical Institute
Position	non
Qualification	Ph.d
Speciality	Civil Engineering/ Water Resources
Email	mohamed.akram@ntu.edu.iq
Phone	07704501917
Address	Northern Technical University/ Technical Institute in Mosul, Mosul, Mosul, Iraq

Time Series Analysis For Rainfall-Discharges Modeling for Selected Basins In Northern Iraq

Apr 28, 2008

Journal Al-Rafidain Engineering Journal

DOI https://doi.org/10.33899/rengj.2008.44563

Issue 2

Volume 16

The Dynamic Regression model (DR) was used for forecasting the inflow to the Mosul and Dokan dams considering the effect of rainfall on the discharges. The auto correlation function (ACF) was used to determine the stationary level of the time series. The partial auto correlation function (PACF) was used to identify a suitable ARIMA model for time series of rainfall and discharges for both dams. Besides, the other statistical tests: (χ2-test, t-test, RACF, Normality test, Trend analysis, CCF, Box-Cox method, Skewness Coefficient), and the factors of the transfer function models (TF) were determined. After passing the suitable statistical tests and the dynamic regression model for both dams, the model became suitable for forecasting the inflow depending upon the historical discharges and rainfall data. Key words: Transfer Function – Dynamic Regression- Rainfall- Discharges- Modeling.

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Flow simulation over oblique cylindrical weirs

Apr 15, 2015

Journal Canadian Journal of Civil Engineering

publisher NRC Research Press

DOI https://doi.org/10.1139/cjce-2014-0157

Issue 6

Volume 42

This paper presents a computational fluid dynamics (CFD) simulation to investigate the effects of the obliqueness of cylindrical weirs on the flow velocity distribution, the pressure distribution and the distribution of water depth over the weir crest. Three different cylindrical weirs with diameters of 0.114 m, 0.09 m, and 0.0635 m, with three dissimilar inclination angles of 90°, 135°, and 150° were used. The SSG Reynolds stress turbulence closure model was utilized in the analyses. The results show that the flow patterns are affected by the inclination angle with respect to the flow direction. It was noticed that inclination angle increment increases the velocity of flow at the downstream surface of the weir, thus increases the absolute value of the negative pressure, at the inward-moved end of the weir. The outward-moved end of the weir was observed not to be covered with water and extending with the increase of the inclination angle.

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Simulation and comparison of helical and straight-bladed hydrokinetic turbines

Mar 1, 2018

Journal International Journal of Renewable Energy Research

Issue 1

Volume 8

In this article simulation analyses have been performed using computational fluid dynamics techniques to investigate the performance of helical and straight-bladed cross flow hydrokinetic turbines with a horizontal layout and similar dimensions. The length and diameter and the type of the hydrofoil of both turbines are selected to be the same. A symmetrical NACA hydrofoil has been used in blade design for both turbines. The simulation analyses were performed for a 2-D NACA0018 hydrofoil and 3-D four bladed turbines. The skewness coefficient and the orthogonal quality tests have been dependent as statistical tools to examine the quality of the mesh for all models. The obtained results have shown that the helical turbine reaches the stall condition at the tip-speed ratio (TSR) of 3.75, while the straight-bladed turbine stops converting energy at 3.1. The highest power coefficient for the helical turbine was about 0.37, while it was found to be around 0.29 for the straight-bladed turbine. These results demonstrate that a helical turbine of 1.5 m in length and 1 m in diameter is more efficient than the same-sized straight-bladed turbine under the same flow conditions.

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Evaluation of flow behavior over broad-crested weirs of a triangular cross-section using CFD techniques

Aug 19, 2018

Journal The Eurasia Proceedings of Science Technology Engineering and Mathematics

publisher ISRES Publishing

Issue 2

Weirs are barriers placed across a river and designed to control the flowing water in order to prevent floods, make waterways operable for inland navigation and measure flow discharge. Although there are many types of weirs, mainly used ones are sharp-crested, circular-crested (cylindrical), broad crested and ogee weirs. In the present study, triangular broad-crested weirs are numerically investigated under different flow conditions. Different interior angles of 90o, 100o, 110o and 120o are included for the opening of weirs. The flowing water over weirs is simulated using CFD techniques and evaluated at different flow regimes with inlet discharges of 0.012 m3 s-1, 0.036 m3 s-1and 0.06 m3 s-1. The simulation results have shown that the water level upstream the weir is inversely proportional to the opening angle, where an increment of 10o in the opening angle leads to a drop in water level about 1.5 cm. In addition, applying a discharge of 0.012 m3 s-1, an uncovered region with water is created downstream the triangular broad-crested weirs, while the bed downstream of the rectangular broad-crested weir is covered with a thin layer of water at the same flow discharge. The aforementioned results are compared with a comparative data and show good agreement. By using triangular broad-crested weirs, it is important to measure the wake region and the hitting point of falling water downstream the weirs where this area must be strengthened well in order to resist water power and reduce the risk of drift.

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Investigation the Performance of Stream Water Wheel Turbines using CFD Techniques

Aug 19, 2018

Journal The Eurasia Proceedings of Science Technology Engineering and Mathematics

publisher ISRES Organizasyon Turizm Eğitim Danışmanlık Ltd. Şti.

DOI https://doi.org/10.6703/IJASE.202206_20(2).007

Issue 2

A stream water wheel is a machine for converting the energy of moving water into power. It consists of a large metal wheel, with a number blades arranged on the outer rim which allows the wheel to be rotated by the water striking the blades. Water wheels were used since ancient as a primary source of power. It was used for irrigation, grain milling and supplying villages with water. In the present study, a stream water wheel turbine of 5 m in diameter is numerically simulated using ANSYS-CFX package under different flow conditions. The wake region behind the turbine is monitored where it influences on other turbines next to it. The simulation results have shown that in case of constructing a farm of wheel turbines, the streamwise span should not be less than 6 m. The stream wheel turbines works normally at a tip speed ratio TSR less than unity.

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Numerical evaluation of helical hydrokinetic turbines with different solidities under different flow conditions

Sep 11, 2018

Journal International Journal of Environmental Science and Technology

publisher Springer Berlin Heidelberg

DOI https://doi.org/10.1007/s13762-018-1987-1

Volume 16

In the present study, the effect of the turbine solidity on the performance of helical cross-flow hydrokinetic turbines is numerically investigated under different flow conditions. Four turbines, with different solidities of 0.15, 0.2, 0.25 and 0.3, were investigated in five dissimilar flow conditions with Froude numbers of 0.0714, 0.143, 0.214, 0.286 and 0.357. The devices employed in the analyses were three-bladed with the diameter of 1 m and length of 1.5 m. They were positioned horizontally in a rectangular-shaped channel with a perpendicular alignment to the flow direction. Symmetrical NACA0018 hydrofoils, which are twisted with an angle of 120°, were used in the blade design. The investigation results have shown that the turbines with the solidity values 0.15 and 0.2 are more efficient than the other two cases. Considering all five flow conditions, the models have displayed the worst performance at a tip speed ratio of 4.0.

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Evaluation Of Flow Behavior Around Bridge Piers

Jan 2, 2020

Journal Solid State Technology

publisher NeuroQuantology

Issue 6

Volume 63

In the present study, the flow behavior around piers of different shapes is investigated at three different flow conditions of Froude numbers of 0.16, 0.32 and 0.64. Simulation analyses were performed using CFD techniques with the support of the ANSYS-CFX package. The obtained results have shown that the minimum eddy viscosity of 0.18 Pa s was noticed behind the cylindrical pier while the maximum value of about 0.49 Pa s was determined behind the triangular pier of downstream head. At a very low Reynolds number of 38, laminar flow, a pair of symmetric vortices are created just behind the cylindrical pier. Von Karman Vortices are created behind the piers under study at transient and turbulent flows. Regarding the drag force hitting the piers, the cylindrical shape was less subjected to drag force of water unlike the triangular pier of the downstream head, which shows the highest resistance. Due to the flow resistance, a pressure drop is created behind the piers. The cylindrical pier shows minimum drop of water level of about 0.46 m while the maximum value of about 0.64m in average was noticed behind the triangular piers. The cylindrical pier shows the best performance where the flowing water is less disturbed. The hexagon and square piers come in the second level where it is possible to use them instead of cylindrical piers if the architectural issue is urgent and here additional protection of the foundations is needed.

Assessment of Multi-blade Savonius Hydrokinetic Turbines

Aug 2, 2022

Journal NeuroQuantology

publisher NeuroQuantology

DOI DOI:10.14704/nq.2022.20.9.NQ44009

Issue 9

Volume 20

The water energy was the most available clean and eco-friendly source of power and it is not exploited efficiently. In the present study, different types of savonius turbine are numerically simulated using CFD techniques in order to evaluate the performance under different flow conditions of flow velocity of 0.5 m s-1, 1.0 m s-1 and 2.0 m s-1. 2-bladed, 3-bladed and 4-bladed turbines were considered in this work with constant dimensions of the blades in all models. The turbulence eddy dissipation and drag force parameters are dependent as measures of the turbine efficiency. The simulation results show that the 3- bladed turbine generates more energy due to its ability to resist the flow of high drag force which results in high eddy dissipation unlike other models. This is due to the suitable blockage area of the 3-bladed turbine that increased the performance.

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Effects of upstream and downstream ramp on flow characteristics over a cylindrical weir

Jan 2, 2023

Journal International Journal of Applied Science and Engineering

publisher ISRES Publishing

DOI https://doi.org/10.6703/IJASE.202206_20(2).007

Issue 2

Volume 20

Cylindrical weirs are one of the most commonly employed hydraulic structures to measure flow, compare to other types of the same width they pass larger discharge. This paper presents an experimental work together with a CFD simulation to study the effects of the geometric characteristics of a cylindrical weir and a ramp placed upstream or downstream of the same weir on the discharge coefficient. Three different weir diameters and three ramp angles under three different discharges were utilized. The results show that the geometric characteristics represented by the diameter of the weir affects the discharge coefficient when there is no ramp. The discharge coefficient was observed to decrease as the slope of the upstream ramp was increased, however as the slope of the downstream ramp was increased the discharge coefficient was noted to increase. A mathematical relationship was developed in order to calculate the discharge of flow passes over the cylindrical weir depending on its diameter.

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Investigation of Flow Hydraulic Gradient Through Self-Spillway Dams

Jun 11, 2024

Journal Salud, Ciencia y Tecnología-Serie de Conferencias

publisher AG Editor (Argentina)

Dams are hydraulic structures constructed across rivers in order to store or rise water level for multi-purposes such as irrigation and power generation. The upstream face of the dam is subjected to water drag force which makes possible of flow seepage through the dam body. In the present study, the difference in water level between upstream and downstream sides of a rock-fill dam is investigated under different flow conditions demonstrating the flow behavior through the dam body. Two well graded samples of river aggregates with d50 of 56 mm and 40 mm are used to build the dam model. One sample of poor graded crushed rocks of d50 33 mm is included as well. The obtained results show that due to the porosity of the gabion containing the aggregates, the hydraulic gradient line dropped down significantly where it is inversely proportional to the porosity non-linear relationships for all. In addition, a linear relationship has dominated on the relation between upstream water depth and discharge through the self-spillway dam with and without impermeable core

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