Assessment of turbulent heat flux models for URANS simulations of turbulent buoyant flows in ROCOM tests

Turbulent mixing in buoyant flows is an essential mechanism involved many scenarios related to nuclear safety power plants. Comprehensive understanding and accurate predictions of turbulent the reactor are crucial importance, due function mitigating potential detrimental consequences during postulated accidents. The present study uses URANS methodology investigate buoyancy-influenced pressure vessel under main steam line break accident scenarios. With a particular focus on influence heat flux closure models, various combinations two turbulence models three utilized for numerical simulations ROCOM tests which have different characteristic features terms flow rate fluid density difference between loops. simulation results compared with experimental measurements so-called scalar downcomer at core inlet. shows that anisotropic able improve accuracy conditions strong buoyancy whilst weak case, major role played by selected essentially negligible models.