Tridimensional core transient analysis methods (TRICOT): The porous medium model PORFLO for 3D two-phase flow and its application to BWR fuel bundle simulations

This presentation describes the current status of the PORFLO code and the latest developments made in the second subtask of the SAFIR2010/TRICOT project. The present work is a continuation of the corresponding previous SAFIR project. In PORFLO, the basic features of the computer code include assumption of porous medium, description of the problem in Cartesian coordinates and the use of either the five-equation model (with a mixture momentum conservation equation) or the six-equation model for the solution of the two-phase flow problem. The most important development steps made during 2008 were: the implementation of the six-equation model to PORFLO and the development of new iterative solvers and preconditioning methods for the solution of the pressure correction equations of both the five-equation SIMPLE algorithm and the newly developed (six-equation) Phase-Coupled SIMPLE algorithm. As a result of the new iterative solvers and preconditioning methods the computation time has been reduced almost by an order of magnitude.