Numerical solutions are presented for mixed convection from an array of circular cylinders embed in a saturated porous medium. The cylinders are at constant temperature(isothermal) and arranged in a staggered tube bank. Both aiding and opposing flow conditions are considered. Numerical calculations using finite difference method with body-fitted coordinates have covered a wide range of governing parameters(i.e.,10 ،ـ Re ،ـ 100, 0 ،ـ Gr ،ـ 400 and Pr = 0.7). Results are presented for streamline, isotherms and the local and the average Nusselt number at different values of the governing parameters. The present results are compared with previous theoretical results and show good agreement
A numerical investigation of mixed convection from a horizontal cylinder in a saturated porous medium is presented. The governing equations based on Darcy’s law are expressed in a body- fitted coordinate system and solved numerically by explicit method. The direction of the flow varies between the vertically up ward(assisting flow) and vertically downward(opposing flow). Results are presented for Reynolds number Re from 10 to 100 with Grashof numbers up to Gr =5Re. The Prandtl number was kept at a constant value of 0.7. results are presented for the streamlines and isotherms as well as the local and average Nusselt number at different values of governing parameters. Comparison with previous theoretical results show good agreement.
Heat transfer through porous media has gained considerable interest in recent years due to its ability to enhance the thermal performance in various engineering applications. There are two key advantages of using porous materials. First, the effective heat dissipation surface area is larger than that of traditional solid fins, which intensifies convective heat transfer. Second, the irregular motion of fluid around the internal porous structure improves mixing, promoting greater thermal uniformity by breaking the boundary layer and generating vortices, while in contrast, there is a drop in the pressure of the working fluid. This review provides a structured overview of the developments in heat transfer within porous media, focusing on two categories of working fluids: conventional fluids and nanofluids. Each category is further classified according to the flow regime involved: natural, forced and mixed convection. For conventional fluids, porous structures demonstrate considerable improvements in Nusselt number and thermal efficiency in compact heat exchangers and flow channels. For nanofluids, enhanced thermal conductivity and the possibility of coupling with magnetic fields (MHD) show promising results, especially under forced and mixed convection conditions. The findings from this review reveal that while both conventional and nanofluid systems benefit from the use of porous media, nanofluids exhibit superior heat transfer capabilities when properly optimized. Additionally, the effectiveness of porous media strongly depends on geometric properties, porosity, flow regime, and thermal boundary conditions. This paper offers a comparative understanding of these systems and identifies potential directions for future research in advanced thermal system design.
The Cooper-Harper rating of aircraft handling qualities has been adopted as a standard for measuring the performance of aircraft. In the present work, the tail plane design for satisfying longitudinal handling qualities has been investigated with different tail design for two flight conditions based on the Shomber and Gertsen method. Tail plane design is considered as the tail/wing area ratio. Parameters most affecting on the aircraft stability derivative is the tail/wing area ratio. The longitudinal handling qualities criteria were introduced in the mathematical contributions of stability derivative. This design technique has been applied to the Paris Jet; MS 760 Morane-Sualnier aircraft. The results show that when the tail/wing area ratio increases the aircraft stability derivative increases, the damping ratio and the natural frequency increases and the aircraft stability is improved. Three regions of flight conditions had been presented which are satisfactory, acceptable and unacceptable. The optimum tail/wing area ratio satisfying the longitudinal handling qualities and stability is (0.025KeywordsLongitudinal Handling---Stability---Tail Design