Investigation of nanofluid natural convection heat transfer in open ended L-shaped cavities ...

In this paper, laminar natural convection of copper/water nanofluid in an open-ended L-shaped cavity is investigated by Lattice Boltzma Model (LBM). The results are compared by previous studies, that are in good agreement. Influences of Rayleigh number (Ra=〖10〗^3,〖10〗^4,〖10〗^5,〖10〗^6), cavity aspect ratio (AR=0.2, 0.4, 0.6) and volume concentration of Cu nanoparticles (0≤φ≤0.1) on the momentum, thermal fields and heat transfer in the enclosure are studied. Also, the effect of changing the boundary conditions, on the heat transfer rate has been investigated. It is observed that maximum heat transfer enhancement by adding the nanoparticles for Ra=〖10〗^6 with AR=0.4 (32.76%) occurs. Results illustrate that increasing the cavity aspect ratio decreases heat transfer rate for Ra=〖10〗^3 and Ra=〖10〗^4. The least and most heat transfer rate for Ra=〖10〗^5 occurs in enclosures by aspect ratios of 0.2 and 0.4 respectively, while it was observed at Ra=〖10〗^6 for minimum and maximum rate of heat transfer the opposite behavior that at Ra=〖10〗^5 occurs.