A comparative assessment of different experiments on buoyancy driven mixing processes by means of CFD

• Systematic model assessment on basis of similar experiments in different facilities.
• Focus on highly transient and 3D buoyancy driven mixing processes.
• U-RANS approach is capable to capture the phenomenology.
• Impact of initial and boundary conditions on the predicted mixing process identified.
• Experiments need quantification of wall heat transfer and flow pattern.

Containment flows are driven by density differences in the long term of an accident scenario. A systematic CFD validation has been performed and is presented in terms of a comparative evaluation of two different tests in the German THAI and French MISTRA facilities. The simulation results demonstrate the general capability of CFD to predict such flows but also reveal a significant sensitivity to the defined initial and boundary conditions.