HIGH-FIDELITY SIMULATION OF MIXING PHENOMENA IN LARGE ENCLOSURES

In the present work, two Large Eddy Simulations of single isothermal jets discharging into the upper plenum of high-temperature gas-cooled reactors are performed with NekRS, a spectral-element code with GPU capabilities developed at Argonne National Laboratory. The proposed models are verified with their corresponding reference experiments of scaled facilities which were conducted at Texas A&M University and Michigan University. The CFD simulations were performed on Summit supercomputer at Oak Ridge National Laboratory (ORNL). For validation purposes, first and second-order statistics from the CFD calculation are compared with their corresponding experiments in the central plane of the jet flow. The models proved to be accurate as these results are in good agreement. Additionally, the flow behavior exhibited by the CFD models is also in accordance with what was observed in the experiments as well as what describe in previous literature for this type of configuration. It should be noted that the proposed models are part of a broader effort under the current IRP-NEAMS-1.1 project whose main objective is to deliver fast-running models for accurately predicting complex physical phenomena including, for instance, turbulent mixing and thermal stratification. In this context, the CFD models proposed here will be used to generate a robust high-fidelity data-set to be applied in conjunction with data-driven methods to improve turbulence modeling closures.