A numerical study of natural convection effects on a rotating cylinder heated with a heat source on a fixed location

A computational study is presented which investigates the heat loss due to natural convection from a two-dimensional rotating pipe heated with a heat source located at a fixed position on the inner surface of the pipe. The heat source is of two forms, one with constant high temperature and the other with constant heat flux. A linear low-Reynolds number turbulence model is applied to this problem to capture the transition process taken place in the later stage of the flow. Meanwhile, an unstructured-mesh solver incorporated with a sliding mesh technique is employed to perform the calculation. It is found that the transition process poses the greatest impact to the heat loss of this problem. After the transition, the boundary layer on the outer surface of the pipe becomes turbulent, grows much thicker, and heat transfer is largely promoted. It can also be concluded that the onset of transition is closely related to the rate of heat input to the system. The more the amount of heat input, the earlier the onset of transition is. The level of heat loss can be as high as 18% of the total heat input at the end of the second revolution of the pipe.