Flow pattern inside SEN below stopper rod: influence of turbulence models

In continuous casting of steel, the casting rate is often controlled by a stopper rod placed in the tundish outlet where the submerged entry nozzle (SEN) tube begins. The flow pattern inside the SEN plays an important role for the bubble formation at the argon injection nozzle at the stopper rod tip. High flow velocities are reached in the small gap be- tween stopper rod and the surrounding SEN walls, and a flow separation has to be expected after the gap due to the fast expansion of the cross section. PIV-flow measurements in a 1:1 scaled water model of the caster show a highly oscillating and asymmetric flow pattern with rapidly changing separation regions. In numerical simulations, the choice of the turbulence model and the usage or the non-usage of geometrical symmetries for the bound of the com- putational domain have a great impact on the resulting flow pattern and the accuracy of the predicted pressure drop. The results of various turbulence models will be compared with results from measurements.