Development of a novel two-phase flow solver for nuclear reactor analysis: algorithms, verification and implementation in OpenFOAM

A porous medium-based representation of nuclear reactors and complex engineering systems more in general can significantly reduce simulation and modelling costs, while preserving a reasonable degree of accuracy via regime map-based correlations for modelling physical interactions. This paper presents a segregated algorithm for the simulation of dispersed two phase flows in such systems treated as porous media in an Eulerian framework. The global algorithm pertaining to the coupling between the mass, momentum and energy conservation equations solution is discussed and implemented via the finite volume OpenFOAM programming library. In the context of pressure–velocity coupling, a novel implementation of the Partial Elimination Algorithm for the treatment of the inter-phase momentum transfer term is developed. It is found to perform better than existing implementations for a number of cases with important momentum coupling between phases. A conclusive verification of the overall solution algorithm is performed with the Method of Manufactured Solutions and order-of-accuracy testing. From an implementation perspective, the performance of the algorithm in parallel strong scaling up to 4096 cores is assessed and proves to be in line with OpenFOAM-based code standards.