Author: Ali Najim Abdullah

Numerical study of buoyancy driven in an inclined enclosure filled with Al2O3/water nanofluid was carried out. The cold outer circular wall and hot inner elliptic wall of enclosure were maintained at constant temperature TC and Th; respectively. The stream function–vorticity method was used to solve the prevailing calculations which are discretized using the way of finite volume and then resolved via code of FORTRAN. Validation was performed by comparison the current results with previous results and found to be in excellent agreement. The study coved wide ranges of Rayleigh number (104 ≤Ra ≤ 106) and volume fraction were (0 ≤ 𝜑 ≤0.2) with different angles of inclination 𝜙= 0o (horizontal position), 30o, 60o, and 90o (vertical position). Results were presented in terms of streamlines, isotherms, local and average Nusselt numbers. The maximum average Nusselt number is obtained by using nanofluids and it is more pronounced at high Rayleigh numbers. Moreover, the heat transfer rates enhance at higher Rayleigh numbers as the angle of inner cylinder inclination increases. While, at low Rayleigh numbers, there is no effect for changing angle of inclination on the heat transfer process. KEYWORDS: natural convection; buoyancy driven; circular; enclosure; cavity. https://jmerd.net/Paper/Vol.43,No.7(2020)/62-74.pdf      

Fossil fuels are non-renewable, finite,and exhausting. Therefore, it is necessary to find alternative sources of energy.Solar energy is   abundant in nature, so it can be considered as the best alternative to meet the energy demand. It is sustainable, renewable, and scalable. Increasing the efficiency of harnessing solar energy should be one of our top concerns because it is a renewable resource. The challenge in  utilizing this energy is to increase efficiency as well as reduce production costs. So, a dual-axis solar tracker was developed in this study to ensure that the tracked solar cells create more electrical energy than stationary solar cells, improving the performance of the solar panels and expanding their ability to make the most of the solar radiation. The experiment yielded great results. Due to its constant exposure to sunlight, the temperature of the mobile cell is higher than that of the stationary cell. The radiation intensity of the tracked cell is more than that of the fixed cell. The radiation intensity for the traced cell is more than that of the fixed cell and peaks at 1282 W/m2 on September 10 and 1028 W/m3 on September 11. For day 10, there was a daily rate of rise in radiation intensity on the tracker cell of 42 % compared to the fixed. Day 11 saw a difference of 210 W/m2/h, or 61 percent. The results are almost same from midday until dusk. During the day, the tension in the vacuum is somewhat different for stationary cells and tracking cells, with the value of the tracker being marginally lower than the fixed value. The increased temperature in the cell caused by more solar radiation and a warmer environment is thought to be the reason for the lower energy gain in the tracker Keywords: solar tracker, light dependent resistor (LDR), Arduino, solar cells, dual-axis https://doi.org/10.15587/1729- 4061.2022.266256

Enclosure with an inlet at the base and an opposite outlet at the top was investigated numerically using finite element method. The heat was applied to the sidewall of the enclosure away from the inlet opening. The Richardson number was changed a number by the values (0, 1, 2.5, 5, and 10). For each Richardson number, Reynold number was changed into (25, 50, 100, 200, 300, 400, and 500) respectively. Average and local Nusselt number was determined during the investigation as well as the streamlines and the isothermal patterns. The results revealed that as value increases of Reynolds number in the enclosure the Nusselt number was also increased, the same way as Richardson number increased the Nusselt number in the enclosure increased. KEYWORDS: Enclosure, Numerical investigation, Nusselt number, Mixed convection. https://jmerd.net/Paper/Vol.43,No.5(2020)/318-331.pdf