Computational Fluid Dynamic Simulation of Square Array Rod Subchannel

The results are compared against the data available in the literature to check on the simulation accuracy. In the simulation of the subchannel geometry, appropriate selection of the boundary conditions in the gap region is important in obtaining good predictions. The Reynolds stress turbulence model shows improved calculation accuracy over the eddy diffusivity model by accounting for the effect of anisotropy in turbulence. The multiple shear stress peaks differ in the calculation from the test results calling for further investigation. However, the lack of other turbulence related data in the 45 .deg. to 90 .deg. in the same literature may necessitate a dedicated new set of experiment. Crucial safety concerns are imposed upon fuel region where fission reactions take place. The rod array configuration is commonly utilized to maintain good heat transfer characteristics and the structural integrity. Design of the fuel assembly requires the various engineering considerations such as pressure drop, manufacturability, and generation of turbulence. A best way to estimate performance of the fuel assembly is to build a mockup and measure its physical parameters. However, the required cost and time render it rather difficult to perform experiments for all designs. Instead, with advances in numerical simulation techniques, computational fluid dynamics methods are extensively utilized to assist the experiments by reducing the trial and errors in the mockup. A numerical simulation is carried out on the bare square array rod geometry as a preliminary exercise for the grid spacer design