An numerical analysis of thermal hydraulic characteristics in the 37-rod channel is reported. Because of the geometric complexity, a boundary-fitted coordinate system which can transform a complicated rod bundle configuration onto the space of rectangular coordinate with uniform meshes is used. By using the boundary-fitted coordinate system appropriate boundary conditions can be specified at the surface of rod, and according, the local velocity and temperature distributions are properly taken into accounted.
For the fully developed laminar flow, local wall shear stress distribution around the periphery of rod and f Re which is necessary for pressure drop prediction are presented.
About heat transfer, two different thermal boundary conditions are used. Firstly, uniform wall heat flux in the axial direction with uniform wall temperature in all directions. The former and the latter boundary conditions are for a fully developed, and for a developing thermal flow, respectively.
The effects to the thermal hydraulic characteristics from the possible eccentricity in the rod configuration because of manufacturing tolerance or a certain cause during operation are also analysed using the strong point of the boundry-fitted coordinate system.
