Turbulence modelling of a thermal stratification CFD model

Abstract

The OECD/NEA ROSA project test 1-1 was conducted in 2006 with the objective to obtain the multidimensional temperature distributions in cold legs and downcomer during the Emergency Core Cooling System (ECCS) water injection in a Pressurized Water Reactor (PWR) for verification of computer codes and models. In this paper, 3D Computational Fluid Dynamics (CFD) study of OECD ROSA (Rig-of- Safety Assessment) project test 1-1, using the commercial CFD code Ansys-CFX v13 is presented. The analysis was focused on the turbulence models which are the most relevant physical models responsible for models errors. Steady-state calculations were performed with different turbulence models: Standard k − ε, RNG k − ε, Shear Stress Transport and Reynolds Stress Model. Numerical results for all the turbulence models selected could be considered satisfactory for the prediction of thermal stratified flow. However, it is necessary to establish a procedure to evaluate the error and uncertainty due to aspects as mesh refinement, time step and turbulence models.