Most of the large dams designed with complicated geometry in which physical models have been used extensively. Overflow design guidelines has been used for standard geometries, which are fairly simple. For more complex geometries, physical and numerical models studied here was helpful. The disadvantages with the physical models are high costs and that it can take fairly long time to get the results. In this paper we used a numeric method that is called volume of fluid (VOF) to calculate flow rates on three types of ogee spillways. The results were compared and these comparisons showed good proximity between numeric and experimental data. Results provided information on how accurately a commercially available computational fluid dynamic CFD model can predict the spillway flow rate.
Ogee shape spillway was used to control the height and volume of water behind the dam. Geometrical properties affected hydraulic variables were investigated. The most common overflow hydraulic structure was analyzed for considering its optimal safety, cost of operation and maintenance. Based on analysis, geometry, the flow rate and construction cost was sensitive and affected hydraulic properties of the system. A numerical method volume of fluid (VOF) was considered for computational analysis of geometry and hydraulics variables for three types of spillways. Numerical results were compared with experimental observations and measurements provided verification of the model and coding performances. The comparison showed that numerical modeling were enhanced and accurately predicted the multi-variables and objective functions involved in a complicated hydraulic structure operation.
Key words: Shape of spillway, numerical method, volume of fluid, optimized flow parameters, sensitive geometry
Dam is a complicated hydraulic structure used in flood control and water management. Inaccurate computational analysis may cause heavy human and financial damages. Spillway is one of the most important structures associated with the construction of the dam, required to allow excess flood water to drain out from the reservoir. Correct understanding of the flooding over spillways and its modeling provides powerful tool in the design of complicated water structures. Hydraulic works associated in this structure have been critically reviewed in literatures, see; Akbari, Etesam . Under flooding water level behind the dam quickly change and multi-variables impacts on safety and maintenance of the project is reviewed.
Ogee spillway due to its excellent hydraulic characteristics has shown to be a front line research topic studied more frequently. Due to ability of this structure in discharging the flow and measuring the flow rate it has convinced the engineers to use them for a wide range of flow conditions safely.
Reviewing the engineering and numerical analysis, design, operations, maintenance and cost of the project, the geometry of the spillway has shown to play an...