Numerical simulation of natural convection heat transfer of copper-water nanofluid in a vertical cylindrical annulus with heat sources

In this work, natural convection of Cu-water nanofluid in a vertical cylindrical annulus enclosure with two discrete heat sources of different lengths is numerically investigated using the finite volume method with SIMPLER algorithm. The adiabatic unheated portions and the discrete heat sources are mounted at the inner wall. The top and bottom walls are thermally isolated, while the outer wall is maintained at a lower temperature. The effects of nanofluid solid volume fraction on hydrodynamic and thermal characteristics such as average and local Nusselt numbers, streamlines, and isotherm patterns for the Rayleigh number ranges from 10(3) to 10(6) and solid volume fraction ranges from 0 to 0.1 are presented. The heat transfer and temperature of heaters depend on the Rayleigh number, the solid volume fraction of nanoparticles, and the length of heaters.