Mixed convection heat transfer from two aligned horizontal heated cylinders in a vented square enclosure

Mixed convective induced by two aligned horizontal heated cylinders embedded in a square enclosure with symmetrical openings at lower and upper surfaces of the enclosure has been numerically investigated. Navier-Stokes and energy equations have been employed to simulate the behaviours of heat and fluid flow fields. The flow has been considered to be steady, laminar and incompressible flow conditions. The parameters have been covered a wide range of the spacing size between two cylinders (0.3 <= S <= 0.45), opening vent (0.125 <= O <= 1), Reynolds number (50 <= Re <= 400) and Richardson number (0.1 <= Ri <= 10), whereas Prandtl number has been kept fixed Pr = 0.7. The average and local Nusselt numbers (Nu), streamlines and isotherms have been presented for various relevant parameters. Numerical results display that the average Nu from the heated cylinders has been increased with increasing in Ri, Re and opening vent. The increase in the spacing size to S = 0.375 leads to enhance average Nu. The spacing size has a negative effect on the average Nu when the distance between the cylinders exceeds S > 0.375. The optimum improvement in Nu has been found when the spacing size S = 0.375 under full opening size case.