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In this paper, we present a numerical study of natural convection in an inclined enclosure. This was achieved in order to stimulate the convective heat exchanges that occur over the absorber of solar air flat plate collector. The considered model is an inclined enclosure with adiabatic side walls and aspect ratios 1 ≤ AR ≤ 12, and which contain heated air-filled (Pr=0.71). The inclination angle Ө of the enclosure was varied from 00° to 90° with Rayleigh numbers in the range of 10 3 ≤ Ra ≤ 10 6 . The influences of Ө and Ra on the flow patterns are investigated. The analysis is carried out by a numerical solution of the full governing equations; the resolution of the problem is based on the finite volumes method employing a staggered grid arrangement by the iteratively SIMPLE-C algorithm.The results indicate that there was a strong effect of inclination angle on the flow mode transition.

This work investigates the energy extraction mechanism by means of swing arm turbine. The swing arm turbines have a particular motion pattern. The pure translation motion in the conventional flapping turbine changes based on the swing arm rotation. The laminar flow around a NACA0015 is resolved using Computational Fluid Dynamics (CFD) method. The turbine blades are equipped with an oscillating gurney flap for trying to boost the system efficiency. The connected gurney flap oscillates with a given pitching angle. A user defined function and the sliding dynamic mesh technique available in ANSYS FLUENT.15 are used to adjust both of the blade and the flap positions during the turbine flapping cycle. The effects of swing factor and flap length on the system performance are provided. It is shown that the suggested strategy of control is able to alter the pressure distribution during both, the up-stroke and down-stroke phases, which changes the blade aerodynamic forces during all the flapping cycle portions and therefore improving the turbine efficiency.

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In this work, a computational analysis of a spherical solar hot water storage tank during the discharging process is carried out by using the commercial code ansys-fluent.15. The study investigates a new type of spherical heat storage tank. A hinged baffle is fixed at the tank vertical axis to increase the discharge flow rate without a thermocline layer. The dynamic mesh LAYERING technique is used to update the computational domain during the movement of the hinged baffle. The passive pitching of the submerged baffle is due to the fluid-dynamic loads. This model limits the mixture between hot and cold water regardless of the inlet flow rate. A comparative study between tanks with typical diffusers and the hinged baffle model is considered. The comparison of the computational fluid dynamics results with available experimental data showed a good agreement. Examinations of the temperature contours indicate that for the typical models, the interaction between the incoming cold water and the stored hot water gives rise to a thick thermocline layer where its temperature and thickness are related to the intensity of the mixing process. The suggested model shows high stratification efficiency along the discharging process.