NUMERICAL STUDY OF THE EFFECT OF SIDE-WALL INCLINATION ANGLES ON NATURAL CONVECTION IN A 3D TRAPEZOIDAL ENCLOSURE FILLED WITH TWO-LAYER NANOFLUID AND AIR

The influences of side-wall inclination angles of a trapezoidal enclosure filled with two-layer fluids (air and MWCNT-water nanofluid) heated partially from inclined walls on natural convection are investigated numerically. The inclination angles of the side walls varied in a small range of -4.3 degrees <= Phi <= 4.3 degrees which respectively corresponded to the aspect ratio variation of 0.4 < AR < 1.6 for a trapezoidal enclosure. The simulations were performed for the Rayleigh numbers 10(3)<= Ra <= 10(6) and solid volume fractions phi = 0.004 and 0.001. The streamlines, isotherms, local and average Nusselt numbers, and dimensionless velocity in the 3D trapezoidal enclosure are presented. The results show that the aspect ratios or the inclination angles of side walls have considerable effects on the fluid flow and heat transfer characteristics. Also, the local and average Nusselt numbers are increased with increasing inclination angles of side walls, solid volume fractions, and Rayleigh numbers.