3d simulations of single phase flows in rod bundles with ESTET-ASTRID code

The study presented in this paper can be used to evaluate the performance of the ESTET-ASTRID code in the geometry of the Graziella experiment. This experiment which is performed at CEA-Grenoble, reproduces a conventional 5 x 5 rod bundle in thermal-hydraulic conditions equivalent to the normal operating conditions of a PWR core. It gives average subchannel flowrate and enthalpy measurements of great value when validating PWR core thermal-hydraulic codes. A Graziella test point corresponding to isothermal single-phase flow was simulated with ESTET-ASTRID. The influence of the mesh refinement and of the turbulence model (κ-ε, Rij-ε) is studied and we show that a second moment closure model (Rij-ε) in association with a fine mesh (about 400 nodes per subchannel) gives excellent results. The simulations performed indicate that the ESTET-ASTRID local approach and its physical models could bring complementary information, when combined with a subchannel thermal-hydraulic code such as THYC, for rod bundle flow prediction. (author)