Résumé:
This study reports a numerical investigation of free convection, double-diffusive convection, and combined surface radiation with free convection within the annular region of two concentric vertical cylinders. The outer vertical wall is maintained at lower uniform temperature and concentration, while the inner vertical wall is maintained at higher uniform temperature and concentration. The top and bottom horizontal walls are adiabatic and impermeable to mass transfer. The four walls have the same emissivity εwall=1.0. The steady-state continuity, Navier–Stokes and energy equations were carried out by the finite volume method, and the Discrete Ordinates Method (DOM) was used to solve the radiative heat transfer equation (RTE). The coupling between the continuity and momentum equations is solved using the SIMPLER algorithm. The thermal Rayleigh number (RaT) and height ratio (X) are, respectively, varied in the range 103≤RaT≤106 and 0.0≤X≤1.0 for Prandtl numbers (Pr) equal to 0.7. The influence of physical and geometrical parameters on the streamlines, isotherms, isoconcentrations, average Nusselt and Sherwood numbers has been numerically investigated in detail. It is founded that the Surface radiation reduces the convective heat transfer across the cavity.
