Forced convection in a vertical pipe with combined buoyancy and radiation effects

Interaction of mixed convection and thermal radiation in laminar pipe flow is studied. An absorbing and emitting gas is considered and treated to be a gray medium. Under the idealization of gray gas, the radiation contribution is modeled by the method of moments. The effects of buoyancy and radiation on the developments of temperature, velocity, and local Nusselt number are examined in detail. Results show that the radiation effect tends to reduce the buoyancy effect. Additionally, heat transfer rate increases with radiation-conduction parameter N.