Experimental investigations are carried out to study the physics of the flow that passes weir-gate hydraulic structure and encounters obstruction with or without installation of downstream opening. This study approaches the comparison between two different options; the first option deals with free flow condition while the second option deals with submerged flow condition. Various cases are performed considering different hydraulics variables and dimensions variables to evaluate the existence of obstruction with or without openings. Overall the flow pattern is more sensitive to the presence of obstruction at downstream region than in its absence. The hydraulic variables that are considered in the study are divided into dimensional variables such as discharge, downstream flow velocity and water depths at downstream and non-dimensional variables such as discharge coefficient, Froude number and Reynolds number. The obstacles which are used in this study have variable heights with constant width and length. Constant spacing between the obstacles is adopted. Different arrangements of obstacles are considered in this study and it is found that a significant and reasonable result is different among the cases. The effect of rectangular opening in the obstruction on flow pattern is studied. The effect of obstacles with rectangular opening gives a noticeable result in the assessment of the discharge coefficient of the composite hydraulic structure.

A set of laboratory experiments were conducted to study the effect of using a Strip Guide Flow Panel device to reduce scour process effects around a bridge pier. Three cylindrical piers of different diameter values and three different Strip Guide Flow Panel devices were used. Every Strip Guide Flow Panel device is simulated by two arms connected together at one of their edges at a right angle. The length of every arm is selected in a way to cover the pier diameter. Every Strip Guide Flow Panel was mounted on the upstream face of the corresponding cylindrical pier diameter at elevation adjacent to the flume bed. A uniform sized sediment were used as a bed material. Based on the experimental data, an acceptable range of scour reduction efficiency (35.71-66.67%) and high hydraulic safety factors were obtained when using Strip Guide Flow Panel. Also it is found that the scour depth when using Strip Guide Flow Panel is small comparing with corresponding potential and maximum scour depth values. So it can be concluded that the Strip Guide Flow Panel device can work like a turbulence kinetic energy dissipater to reduce the risk of scour around the pier during the serviceability life of bridge structure.

Discordance and concordance play a significant role in the hydraulic response for the flume, open channel, hydraulic structure, and flow field measurement. Bed discordance and bed concordance are regarded as common problems in open channels. Discordance is the dominant one, which could have an effect on the hydraulic structure that is constructed inside the channel. This paper deals with the impact of bed flume discordance on hydraulic flow characteristics at the weir-gate downstream hydraulic regime. Four configurations with different lengths and heights of the bed flume discordance are adopted here to investigate the impact of these configurations on the hydraulic characteristics. In addition, one configuration of the bed flume concordance is adopted to compare with the other four configurations. At downstream, the average water depth becomes dimensionless by dividing by upstream water depth, vertical distance between weir and gate, length of downstream, length of concordance, and length of discordance in order to evaluate the inequality in the distribution of Froude number. On one hand, certain results appear strongly between Reynolds number and Froude number at downstream, actual discharge and flow velocity at downstream, flow area past the gate and Froude number at downstream. On the other hand, there was a complex dramatic relation between the weir-gate discharge coefficient and Froude number at downstream. Overall, the study shows that there is a good relationship between specific energy, water depth, and flow speed. Doi: 10.28991/HIJ-2022-03-03-09 Full Text: PDF

Water flow around cylinder represents a noticeable problem in fluid mechanics. The computational fluid dynamic is employed to study numerically the turbulent flow field around a cylinder without vane and with vane respectively. The vane configuration and direction are considered in the numerical study. The analysis is done in two dimensions by using ANSYS software. The finite volume method is used to model and simulate the cases study. The numerical study concentrates on strain rate, stream function, swirling, vorticity, velocity in the flow direction, radial velocity, pressure distribution, pressure coefficient and drag coefficient. It is recognizing that the vane changes the flow field hydraulic response. It is found from the result that the vane more reduces the value of the drag coefficient as compared with the value of the drag coefficient when the cylinder is alone. The stream function reveal how much the fluid suffer from deformation while the strain rate reveal how much t5he flow velocity change with distance. Also, vorticity illustrate a dramatic hydraulic response especially in the case of the vane existence. The study shows that the vane has direct effect on the flow separation zone and dissipation the turbulent intensity before it passes the cylinder.

Composite hydraulic structure is widely used in irrigation system which consists of two parts. The first part is responsible for overflow regime and is represented by a weir, whereas the second part is responsible for underflow regime and is represented by a gate. Both elements play significant role to control, measured, and divert the flow. So it dominates the hydraulic regimes of open channel or river with high responsibility and accuracy. The target of this study is to investigate the effect of the composite hydraulic structure installation at various inclination angles (from 45-135 degree) with the flume bed, which is horizontal, and adopt the normal position of composite device ( angle equal to 90 degree) as guide in discussion with various angles. Several experimental works were carried out in hydraulic laboratory flume at the Basrah Engineering Technical College under free flow condition with various geometrical dimensions of combined rectangular weir and rectangular gate in order to investigate the effect of inclination angle on major flow factors such as actual discharge, discharge coefficient, depth of water in downstream zone of flume, cross sectional area of flow that cross or pass the weir and gate respectively. Also, this study mentions the percentage of increase in discharge coefficient and variation in actual discharge, discharge coefficient and Reynolds Number with cross sectional area of flow that cross the gate.