Hippo: a multiphysics tool coupling MOOSE and OpenFOAM for nuclear fusion applications
Please login to view abstract download link
Nuclear fusion reactors have the potential to provide a reliable, low-carbon energy source with abundant fuel and without the long-lived radioactive waste associated with fission reactors. However, fusion reactors operate in complex multiphysics environments with strong magnetic fields and high heat and neutron fluxes, which complicate experimental testing and hence require the development of numerical tools capable of capturing the wide range of physics \citep{Garcia-Gasulla2025}. In this study, we present the current progress on Hippo, a multiphysics application that couples the CFD software OpenFOAM with the finite element framework MOOSE. This integration enables the comprehensive CFD capabilities of OpenFOAM to be used within the MOOSE framework, which includes modules for heat transfer, structural mechanics, and 1D thermal hydraulics, as well as a variety of third-party applications, including the Monte Carlo neutron transport code OpenMC.\par To demonstrate Hippo's capabilities, we perform two case studies. First, we present a conjugate heat transfer study of a hypervapotron, a device used in fusion reactors to handle heat fluxes \(>20MW/m^2\). The current results overpredict the measured temperature, with the fluid temperature locally exceeding the saturation temperature. We intend to add a boiling model to the simulation to improve the agreement with experimental results. Second, we perform a multiscale simulation of a natural circulation loop where most of the loop is modelled using a 1D thermal-hydraulics network in MOOSE, and a small section is modelled with OpenFOAM using a non-overlapping domain approach. This approach significantly decreases the computational cost compared with a full CFD model. We observe good agreement compared with a previous numerical study \citep{GRUNLOH201785}. Some important next steps in Hippo's development include adding volumetric coupling capabilities to enable coupling with OpenMC and applying Hippo to challenging fusion test cases such as breeder blankets.
