Design of a CFD scheme using multiple RANS models for PWR

Abstract Without efficiency, the CFD simulation of a reactor will not be affordable. However, numerous narrow flow channels with thousands of complex spacer grid exist in a typical pressurized water reactor (PWR) core. The huge burden in both computational resources and time is a key challenge. To realize a reduction of the computational burden, research on flow characteristics affected by RANS models and typical structures of PWR have been done. Based on the flow characteristics, a CFD scheme was designed by a hybrid application of multiple RANS models (MRANS). Different from the traditional turbulence scheme which just use one single RANS model, MRANS keeps the isotropic RANS models used in the major domains, and the anisotropic RANS modes used in the small local domains. After some validations, it was found that MRANS can successfully keep the accuracy and improve the computing efficiency by nearly two times. This superiority in efficiency could play an important role in the CFD simulation for a whole PWR.