Laminar natural convection in a vertical isothermal channel with symmetric surface-mounted rectangular ribs

In this paper, a numerical investigation of laminar natural convective flows in a vertical isothermal channel with two rectangular ribs, symmetrically located on each wall, is carried out. The governing elliptic equations are solved in a two-dimensional domain using a control volume method and the SIMPLER algorithm for the velocity–pressure coupling is employed. Special emphasis is given in the systematic analysis to detail the effects of the location of the isothermal ribs on the flow structure and isotherms pattern. The profiles of the local Nusselt number are presented for three different locations of the obstructions, near the inlet, at the center and near the outlet of the channel. The influence of the rib conductivity is also considered, the ribs being either perfectly conducting or adiabatic. The variations in the mean Nusselt number and inlet flow rate versus the channel Rayleigh number are investigated. Finally, for centered ribs extra computations are performed for various sizes (width and length) of the ribs and for two aspect ratios to demonstrated the significant effects on the flow and heat transfer characteristics.