Natural convection heat transfer under constant heat flux wall in a nanofluid filled annulus enclosure

In this investigation, the Control Volume based Finite Element Method (CVFEM) is used to simulate the natural convection heat transfer of Cu–water nanofluid in an annulus enclosure. The Maxwell–Garnetts (MG) and Brinkman models are also employed to estimate the effect of thermal conductivity and viscosity of nanofluid. The governing parameters are the Rayleigh number, nanoparticle volume fraction and the aspect ratio (ratio of the outer radius to the inner one). Results are presented in the form of isotherms, streamlines, local and average Nusselt numbers. The results indicate that increment of the aspect ratio increases the value of average Nusselt number. Moreover, the angle of turn for the boundary condition of the inner cylinder significantly affects the values of local Nusselt number, average Nusselt number, streamlines and isotherms