Direct Numerical Simulation of the Stable Stratification Transient in the HiRJET Facility*

Stable stratification inhibits the natural circulation in the coolant loop and poses safety challenges in the sodium fast reactors. The poor performance of the present engineering turbulence models in buoyant mixing flows urges the high-fidelity data to support the improvement of turbulence modeling. In this work, direct numerical simulation is carried out to simulate the density stratification experiment in the High-Resolution Jet facility. Current simulation has covered the early stage of the stratification transient. It has been seen that the stratified front is highly turbulent initially due to the jet impinging and turbulent mixing effect. As time goes, the stratified front gradually stabilizes and separate from the mixing zone. Position of mixing zone, stratified fronts and the value of maximum density derivative are quantified by curve fitting and the agreement with the experimental results is observed.