Heatline visualization of natural convection heat transfer for nanofluids confined within parallelogrammic cavities in presence of discrete isoflux sources

Abstract

Natural convection in a parallelogrammic enclosure filled with different types of nanofluids (Al 2 O 3 , Ag and TiO 2 ) subjected to three discrete heated isoflux is examined numerically by using a heatlines visualization method. The position of three discrete isoflux are at left and right sidewalls remark by (λ = 0.25), while the third isoflux at a bottom wall remark by (ζ = 0.5). The top wall with the remaining regions in the bottom wall is insulated, while the remaining regions in the side walls are maintained at low temperatures. Finite element method based on a Chorin's algorithm used to solve the governing equation continuity, momentum and energy. Numerical calculations were achieved for a wide range of Rayleigh numbers (10 4 ≤Ra≤10 7 ), skew angle (−30 o ≤γ≤+30 o ), and volume fraction of nanoparticles (0≤ Φ≤0.2). The result is explained in term of stream functions, isotherms, heatfunctions, local and average Nusselt numbers. It is found that the heat transfer performance considerably improve with the supplement water of various species of nanofluid and changing skew angle. Furthermore, nine correlations are established to approximate the average Nusselt number.