COMMIX-1A analysis of fluid and thermal mixing in a model cold leg and downcomer of a PWR

Fluid and thermal mixing in a model cold leg and downcomer of a PWR was analyzed using COMMIX-1A. The present analysis differs from previous analyses in three major aspects. First, extremely fine meshes were used to minimize numerical diffusion in the analysis. Second, one-equation (k) turbulence model was used to better model the turbulent flow. Third, curved surfaces were modeled by several slanted planes to better represent the geometries. By using these improvements, CREARE 1/5-scale test No. 51 was reanalyzed. Significant improvements were achieved in the comparisons between the COMMIX calculations and the experimental data