INVESTIGATING THE NATURAL CONVECTION HEAT TRANSFER FROM TWO ELLIPTIC CYLINDERS IN A CLOSED CAVITY AT DIFFERENT CYLINDER SPACINGS

A numerical investigation is presented to survey the laminar natural convection heat transfer around two elliptic cylinders with different vertical spacings relative to each other in a closed cavity. The numerical model used in this paper is based on a 2D Navier-Stokes incompressible flow momentum and energy equations solver on an unstructured grid. Discretization of the governing equations that include the continuity, momentum, and energy equations is achieved through a finite element scheme based on the Characteristic Based Split (CBS) algorithm. The working fluid is assigned a Prandtl number of 0.71 (air) and assumed to be incompressible with constant physical properties. The radiation, viscous dissipation, and pressure work are also assumed to be negligible throughout this investigation. Fluid flow and heat transfer characteristics are examined in the range of the Rayleigh number, cylinders spacing, and cylinders' orientation such that: 10(3) <= Ra <= 10(6), 1 <= s/a <= 4, and b/a = 0.67, 1.5. It is also assumed that cylinders' location can be changed vertically along the square cavity centerline. The local and average Nusselt numbers streamlines, and isotherms are presented for various relevant dimensionless groups. The obtained results reveal that the Rayleigh number and cylinders' position would change magnitude and patterns of streamlines and isotherms.