The spillway is an important structure in the dams, used to pass the flood wave to the downstream safely. In the past decades, Computational fluid dynamics (CFD) has evolved. Research findings have shown the CFD models are a great alternative for laboratory models. According to it, the flow pattern over ogee spillways can be studied in a short time and without paying high expenses. Because the flow over the ogee spillway is turbulent and has a free surface, its properties are complex and often difficult to predict. Therefore, the present paper focuses on the study of turbulence closure models including the standard k-ε, RNG k–ε, k–ω, also, the large-eddy simulation (LES) models, to assess their performance to simulate flow over the spillway. The Flow-3d software with the volume-of-fluid (VOF) algorithm is applied to obtain the free surface for each turbulence model. The results of the analysis show that the LES model yielded better results when compared with laboratory results, while the turbulence closure models result of Reynold average Navier Stocks equations (RANS) was more stable, especially standard k-ɛ and RNG models.
Secondary clarifiers form a crucial component in gravity separation processes mainly in solid-liquid separation. They perform the crucial process of separating the activated sludge from the clarified effluent and also to concentrate the settled sludge. As treatment plants receive increasingly high wastewater flow, conventional sedimentation tanks suffer from overloading problems which result in poor performance. Inlet baffle modification by using an energy dissipating inlet (EDI) was proposed to enhance the performance in the circular clarifiers in Al-Dewanyia wastewater treatment plant. A 3-Dimensional fully mass conservative clarifier model was applied to evaluate proposed tank modification and to estimate the maximum capacity of the existing and modified clarifiers. A Computational Fluid Dynamics (CFD) model was formulated to describe tank performance and design parameters were obtained based on the experimental results. The study revealed that velocity and SS are better parameters than TS, BOD5, and COD to evaluate the performance of sedimentation tanks. Removal efficiencies of suspended solids, biochemical oxygen demand, and chemical oxygen demand were higher in the EDI (Baffle).
In recent years, Iraq suffers from exacerbation of the deficit of electrical energy as well as the great environmental pollution resulting from the use of traditional fuels. This called for serious thought to search for using clean and renewable energy sources may available in Iraq.In the present study; small hydropower (i.e. Archimedes screw turbine) are specifically used with a low head at Ramadi Barrage in Iraq. This type of small hydropower station is suitable to apply because not need high storage water or high head in Barrage. The power production in this technology depends on the parameters of the location in which it is placed such as (length L, angle of inclination α, Diameter D,….). The physical model of the Archimedes screw turbine is applied to determine the optimal α. The solid work package with a combination of Computational Fluid Dynamics (CFD) analysis by ANSYS have been used to simulate numerically a three dimensions model to determine the value of power that could be produced by the Archimedes turbine in the Ramadi Barrage. The turbine's performance are tested on two cases which represent low and high discharge investigations with different α (18⁰, 23⁰, 30⁰, 35⁰) based on different flow conditions and different water head between upstream and downstream of the barrage. The results showed that the maximum power production from the barrage is 280,000 watts with α=35° and efficiency η=89.9% for case 1; while; this power becomes 400,000 watts with α=30° but of efficiency η=84.9% for case 2. It is concluded from this research that power production from Ramadi Barrage could be investment to eliminate the deficit in the electrical energy in Iraq.