Forced Convective Heat Transfer From a Continuously Moving Heated Cylindrical Rod in Materials Processing

The flow and heat transfer associated with the forced convective cooling of an infinite heated cylindrical rod moving continuously along its axis in a circular channel has been numerically investigated. Two different flow circumstances, involving uniform flow at the inlet of the cooling channel in the same as well as in the opposite direction as the movement of the cylindrical rod, are considered in this study. This problem is of interest in several manufacturing processes such as hot rolling, continuous casting, extrusion, wire drawing, and glass fiber drawing. The transport processes are time dependent at the initial stages, following the onset of motion, and usually attain steady-state conditions at large time. The temperature distribution in the solid is of particular interest in materials processing. A detailed numerical study is carried out, assuming an axisymmetric, laminar flow, transient circumstance. The governing full elliptic equations are solved, employing a finite volume method. The transport in the solid material is coupled with that in the fluid through the boundary conditions. The effects of several physical and process parameters such as rod speed, material, free-stream velocity, channel dimensions, and fluid on the temperature and the flow field are investigated. For the opposing flow circumstance, some very interesting phenomena are observed. Notable among these is the appearance of a recirculating region within the fluid adjacent to the moving solid surface, causing a reduction in the heat transfer rate as compared to the aiding forced flow case. Validation of the numerical results is carried out by comparison with earlier experimental results, indicating very good agreement.