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Go to Editorial ManagerThe hydraulic characteristics of dams can be predicted with high precision and reliability of physical and numerical models depending on accurate hydraulic data. The model is operated and simulated to get a more efficient, optimized utilization of the dam. This research included a comprehensive overview and literature examination of the Makhool Dam which is considered one of the most important dams under construction in Iraq. Previous studies of the dam focused on different topics in the operation of the dam and analyses of its properties, part of which focused on the dam ability to manage flood and how it works best with other dams in critical times, and another part studied the properties of the stilling basin, velocity in the dam reservoir, pressure, seepage and other characteristics that affect the operating the dam. Despite this research and the variety of topics discussed, there is no well-established research on the operation of the bottom and emergency spillway of the dam by using computational fluid dynamics (CFD) simulation software. CFD is considered an essential tech because it has an important influence in determining the hydraulic properties of a spillway and studying its effectiveness under different operating conditions. Because the spillway is an important element in the dam body, the research highlighted the necessity of performing a simulation using appropriate CFD software for this part. This research has also reviewed previous research on CFD software and their ability to simulate previously constructed or under-construction dams to analysis of its hydraulic properties.
The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted to simulate the conventional solar heating system, multipurpose solar water heater (MPSWH), and multipurpose solar air heater (MPSAH). The commercial computational fluid dynamics (CFD), AVL Fire ver. 2009.2 was used to solve and investigate the temperature distributions in the absorber plate and riser tube of both solar water and air heater during summer and winter seasons. The RNG k -turbulence model was employed for this CFD study. The present paper was to provide a good understanding of thermal performance for the solar collector at different operating conditions. The experimental setup and physical data of Venkatesh, R. and Christraj, W. [15] were employed as geometric parameters and initial boundary conditions to model and to validate the predicted numerical values. Comparing to the values of temperatures for the conventional SWH and SAH, the predicted results of the MPSWH and the MPSAH showed a good improvement on the thermal performance. These enhancements on the temperature may have been due to the new design adopted in the multipurpose solar heating systems by using riser tubes and headers to the original design of the thermal systems. Additionally, the thermal performance of solar collectors increases with increasing the mass flow rates and thermal conductivity of absorber plate. For validation aspect, the predicted results of all cases examined showed a good agreement against the measured results in terms of temperature distribution levels and thermal efficiencies.
Throughout the flight, aircraft wings continuously struggle against various forces: the forward thrust from the engine, the drag pulling them backward, and sudden turbulence from storms. In contrast, these forces are essential for maintaining aircraft stability. With time, the cyclic stresses can result in the formation and propagation of minuscule cracks in the wings. Cracks growing on the aircraft wing surface manufactured from alloy AL7075-T6, have been investigated when subjected to non-preoperational multi-axial cyclic loading. The results have been evaluated using two methods, numerical simulations and theoretical calculation to evaluate dynamic crack propagation crack growth per cycle (da/dN) at angles of attack 5° and 10°. The results showed that the dynamic crack propagation increases with an increase in the crack length. It was found that the values of the dynamic crack propagation rate at the angle of attack 5⁰ are smaller than the values at the angle of attack 10⁰.
The improvement in solar chimneys' thermal performance and thermal behavior that can be achieved by adding metal foam has been tested in computational work. The flow and heat transfer governing equations for solar chimney models were solved using computational fluid dynamics (CFD). It was solved using the control volume numerical method in ANSYS FLUENT 14.5. It is used to construct a finite volume modeling technique for solving the governing equations and the radiation heat transfer equations. With standard flat absorber plates, the results showed that heat transmission was increased by the inclusion of metal foam (10 PPI), leading to an increase in air velocity at the solar chimney of around 13.3%. The highest average air velocity with 10 PPI drops by 54.4% as the height of the absorber plate changes from 5 cm to 25 cm respectively.
This study investigated numerically and experimentally fluid flow and heat transfer in the desktop PC. Three patterns of the positions of air inlet and outlet were tested to find the best one for cooling. The computer components in the present study are CPU, finned heat sink, power supply, motherboard, CD, HDD and fans. Three components which were generate heat are CPU, motherboard and power supply and there were two openings for air inlet and two for air outlet. The air inlet velocities were 1.2, 1.8, 2.4 m/s with constant CPU fan velocity. The studied parameters were the changed of inlet air velocity, powers of CPU, motherboard and PSU and the positions of inlet air. The numerical results obtained are found in a good agreement with the experimental results. The experimental results show that the maximum temperature was 81 at 16.5 W and 1.2 m/s. Numerical results showed that the CPU temperature reaches 89.6 at 18.5 W and 1.2 m/s. From the results, it was found that; the temperatures of the main components (PSU and motherboard) affected little by CPU power and vice versa, the finned heat sink has higher cooling efficiency and the pattern 1 was the best pattern for CPU cooling.