CWIPI: Coupling With Interpolation Parallel Interface

CWIPI is an open-source library dedicated to the parallel coupling of independent simulation codes for multi-physics research, a field also covered by tools such as MUI (Tang et al., 2015) and preCICE (Chourdakis et al., 2022).It is aimed at anyone wishing to conduct studies and research in this field.It provides MPI-based communication and fully distributed data exchange on non-coincident meshes, including on-the-fly spatial interpolation.CWIPI stands out for its support of a wide variety of spatial interpolation families and a broad range of geometric element types.This extensive spatial capability allows users to leverage solver-specific numerical methods, including finite volumes, finite elements, discontinuous Galerkin, and spectral methods.Advanced users can further combine CWIPI's geometric algorithms with solvers' internal interpolations through callbacks, improving accuracy across highly heterogeneous solvers.CWIPI supports a wide range of interface geometries, from linear, surface, and volumetric elements to higher-order elements with curved edges and faces.Performance-critical algorithms have been specifically optimized for handling coupling cases involving dynamic or adaptive meshes.Recent developments in the ParaDiGM library (Quémerais et al., 2026) now provide dynamic load and memory balancing for large-scale simulations.Ongoing work includes GPU acceleration of geometric algorithms (Cazalbou et al., 2024) and the development of temporal interpolation methods (Simon et al., 2025).