The program FLUTAN for thermo and fluid dynamical applications

The numerical simulation of an experiment in the SUCOS-3D facility with the computer code FLUTAN is the topic of this report. The numerical investigations are related to the single phase natural convection in the optional sump cooling concept of the EPR. Calculations of SUCOS-3D show a stable natural convection flow which is settled by the position of the vertical coolers. This flow is similar to the measured one in SUCOS-2D experiment. Analysis of the measured values of temperature shows that a different behavior of natural convection takes place in SUCOS-3D. Despite of a detailed description of the geometry including the modeling of the temperature probe support structure and of the boundary condition of the vertical coolers, the principal reasons which are responsible for the different behavior of the natural convection in the SUCOS-3D experiment were not found. Examination of the SUCOS-Experiments shows that inconsistencies appear between the experimental results of SUCOS-2D and -3D. These inconsistencies, which are not present in the calculations, were discussed with the experimenters. Despite of this difference between calculation and SUCOS-3D experiment, which is presumably based on a lack of detailed information on the real geometrical and thermal boundary conditions, the previous successful simulation of SUCOS-2D with the identification of 3 d effects shows that the computer code FLUTAN is suited to detailed investigations of this kind of complex experiments. (orig.)