Validation of a multiscale coupling algorithm by experimental tests in tall-3D facility

A multiscale coupling algorithm has been developed and validated through the numerical simulation of the thermal hydraulic behavior of an unprotected loss of flow in the experimental TALL-3D facility. During the loss of flow the system goes from forced to natural circulation flow. TALL-3D is a liquid Lead Bismuth Eutectic (LBE) loop, with an oil-cooled secondary loop, developed according to the requirements for the experimental data for validation of coupled CFD and system codes. In this work we perform the coupling between the multigrid finite element code FEMuS and a system code, by using a defective coupling algorithm of a one-dimensional circuit and a three-dimensional test section with overlapping meshes. A multiscale and multiphysics coupling algorithm has been developed based on open-source SALOME platform. MED data structure and HDF5 functions have been used for all the field operations. The coupled system is solved for different computational cases: laminar natural circulation, turbulent k − ω with SUPG regularization and with standard up-wind regularization for the advection term. Each case is also simulated through two different heat exchange models: with constant and non constant turbulent Prandtl number. These tests show the importance of the coupling approach for the analysis of transient simulations where the three-dimensional phenomena play an important role.