Abstract: In the present study, mixed convection in a horizontal
rectangular duct using Al2O3 is numerically investigated. The effects
of different Rayleigh number, Reynolds number and radiation on
flow and heat transfer characteristics are studied in detail. This study
covers Rayleigh number in the range of 2 × 10^6 ≤ Ra ≤ 2 × 10^7 and
Reynolds number in the range of 100 ≤ Re ≤ 1100. Results reveal that
the Nusselt number increases as Reynolds and Rayleigh numbers
increase. It is also found that the dimensionless temperature
distribution increases as Rayleigh number increases.