Sharif Digital Repository

Chutes and stepped spillways are used to provide controlled release of flows and overflow in flood regimes from a dam into the downstream area. The main purpose of steps is to produce considerable energy dissipation along the chute and reduce the size of the required downstream energy dissipation basin. Many researches conducted on this matter and the effects of different factors like the height of steps, the number of steps, the different shapes of steps – mild step and end-sill step – influencing on energy dissipation have been studied. In this study, three different stepped spillway experimental models with different heights (5, 8 and 10 cm) and different number of steps developed, and... 

Sharp crested weirs are one of the main and oldest means of measuring discharge in water conveyance systems. Many studies have been done on sharp rectangular weirs and have provided many relationships regarding the effect of geometric parameters and various factors on discharge coefficient of the weirs.In some places, due to existence of obstacles or barriers in the channel, it is impossible to create a symmetrical continuous weir some other cases,multiple or asymmetric weirs should be used, which is the main concept of this project.Since it seems unlikely that a purely mathematical model can review the impact of the multiplicity and asymmetry of these weirs without using empirical... 

One of the miscellaneous units that are frequently used in water and wastewater systems is flush tank. Flush tank increases the self cleaning velocity in the conduit, and helps to clear the conduits from deposits and contaminations. While these units have been used for many years, there is not enough information about the hydraulic performance of these units in respect to the discharge, distance from the tank and the pipe hydraulics. In this paper the experimental results from observed hydrographs at different distances from the flush tank in a pipe has been presented. The variables include; volume of releasing water (or inlet hydrograph), upstream head, pipe diameter (3 and 4 cm), pipe... 

One of the most important methods of controlling discharge in water industry which is widely used in irrigation, water distribution, waste-water engineering, drainage, flood control and other water related projects, is side weir. The hydraulic behavior of flow over side weir is spatially varied flow with decreasing discharge. Various investigators have related the weir discharge coefficient as a function of main channel upstream Froude number and the fraction of weir height to upstream depth . Performance of sharp crested side weirs with extended length (as labyrinth side weir with asymmetric geometry) has been studied in this thesis. The variables for this study are height of weir ,... 

Aquatic canopy zones play an important role in maintenance of ecosystems. These areas are ubiquitous near rivers, lakes, lagoons, estuaries and shore lines. Governing dynamical systems through these areas have direct influence on, how nutrients and other vital materials for living things disperse. Also, they can control the amount of dissolved oxygen within the body of water in these regions. Nowadays, investigating the effects of vegetation grabbed the attention of many scientists and is a very important burgeoning field. In this study, the effects of surface cooling which resulting from mild wind blow have been investigated. In fact, two type of different currents form when wind blows... 

Slug Flow is one of the most important schemes of two-phase air/water flow, which is quite complex and quite different to a single-phase flow. Also one of the common water conveyance systems is a rectangular tunnel which may have adverse slope at some parts of the tunnel. In this study the hydraulic of slug flow in rectangular tunnels with variable slope from horizontal to adverse have been considered using experimental setup. About 150 tests were carried out for different air/water discharge ratios and adverse slopes, and dynamic pressure fluctuations together with the slug period were measured. It was observed that the pressure fluctuations increase as the air to water ratio increases and... 

Accurate prediction of relative permeability for various reservoir rocks at various saturation conditions has been of concern for a long time in petroleum industry. Relative permeability is known as one of the most significant parameters in simulation of actual multi-phase flow through porous media during life-time of a hydrocarbon reservoir. In addition, it plays important role in oil production and well completion. Direct experimental measurement in order to determine relative permeability of porous rock has long been recorded in petroleum related literature. However, empirical methods for determining relative permeability are becoming more widely used, particularly with the advent of... 

Resources management is essential duo to sustainable development and marine resources limitations. There are several ways to restore coastal damaged ecosystems, one of the best and most cost effective solution is establishment of artificial reefs. A popular type of artificial reef is named Reef ball, a hollow hemisphere. In some regions these habitats has also been used as submerged breakwater. These structures recover and protect endangered species ecosystem although they provide aesthetic view to a beach. Main application of these structures is to provide a safe environment for marine creature. In this study initially Transmission coefficient variation in two-dimensional model experiments... 

Study of hydraulic characteristics of two-phase flow is one of the important issues in hydraulic engineering. Two-phase flows usually accur in hydraulic structures such as pressurized flow tunnels, culverts, sewer pipes, junctions, and similar conduits. Under certain conditions, air may also be introduced into pressurized intake systems, which may form large bubbles in portions of the pipe. The bubbles may, in turn, cause an unstable slug flow, or other flow patterns. Slug flow is one of the most probable patterns in these flows. Prediction of pressure in this situation is a complex subject which despite its great importance is rarely discussed. In this study, the results of a laboratory... 

Sharp crested weirs are one of the main and oldest means of measuring discharge in water conveyance systems. Many studies have been done on sharp rectangular weirs and have provided many relationships regarding the effect of geometric parameters and various factors on discharge coefficient of the weirs.In some places, due to existence of obstacles or barriers in the channel, it is impossible to create a symmetrical continuous weir some other cases, multiple or asymmetric or curved weirs should be used, which is the main concept of this project. Since it seems unlikely that a purely mathematical model can review the impact of the multiplicity and asymmetry of these weirs without using... 

Supercritical airfoils are designed for transonic flow to reduce the strength of shock and its drag. These type of airfoils are used in design and construction of commercial airplanes because of their low drag in transonic regime and, as a result, a reduction in fuel consumption. Using supercritical airfoils needs accurate investigation of flow field due to several influential factors such as their specific geometry, nonlinear nature of flow phenomena, and compressibility effects. However, the availability of experimental and numerical data for supercritical airfoils is less than that for conventional airfoils. Thus, conducting experimental tests is essential for understanding of flow field... 

Air enterance in to flowing water is something that is commonly seen in the water conveyance systems. The mixture of Air and water that flow together create a kind of flow that is called two phase flow. This kind of flow is often seen in culverts and water conveyance systems. There are different flow patterns in two phase flow. Considering pressure fluctuation, pressure drop and pressure recovery, slug flow pattern is the most complicated pattern among all.
Sometimes a singularity is used in a tunnel; one of the singularities that are frequently used in water conveyance system is expansion transition. In this study an experimental setup is used to model two phase slug flow, which passes... 

Oil is being discussed as the main source of producing energy in the world. Thus its exploration and exploitation from the sea or land is very important. Most of these resources exist in the depths of the sea. Exploitation of these resources demands to reach knowledge of design and technology of manufacturing platforms and devices for exploitation in the deep waters. There are massive oil reserves in the context of deep waters. Using fixed platforms in depth is very uneconomic; also we know the natural period of these structures is close to the wave period in deep waters. As a result researches and mining industry in the deep waters have gone to use comparative platforms such as: TBT, TLP,... 

The plant's drag force, in addition to changing the amount of flow velocity within the canopy area, may also alter its structure. In the present study, the aim is to carry out a series of experiments to investigate the energy regime in the exchange flow caused by the phenomenon of surface cooling. In previous studies, the focus was on inertial and viscosity regimes in the lab, while in the present study, about the occurrence of the energy regime in nature, attempts are made to see the energy regime in the laboratory. In this research, PIV technique was used to determine the flow rate in depth. The variation parameters in these studies are the volume percentage of vegetation cover (φ), free... 

In past few centuries , dams have been always a crucial part of human life . Using dams for agriculture and supplying water for people , has made them a valuable asset for countries . So evaluating dam safety and dam breach properties is so important. This issue is a geotechnical , structural and hydrological matter. Safety of earth dams could be threatened due to dam body breach caused by overtopping or pipping, during heavy floods, strong ground motions or any structural damage or defection. As in previous studies , calculating the final geometrical breach properties and time of failure was the main goal , we tried to connect this characteristics and find the relation of time and breach...