A Consistent Interface Reconstruction and Coupling Method for Multiphysics Simulations

Abstract: Accurate representation of interfaces and flux exchange is vital for coupled multiphysics simulations across a broad range of applications. Currently, coupling approaches are limited by the underlying discretization or to specific physical problems, restricting their generality. To remove these constraints, a consistent interface reconstruction and coupling method has been developed to bridge multiphysical computational domains. The proposed numerical framework contains two complementary steps. The first step reconstructs a continuous bounding surface from discretized spatial data using a weighted interpolation and marching-grid approach that preserves geometric fidelity across a wide range of resolutions. The second step consists of a conservative flux mapping algorithm that projects surface quantities such as aerodynamic loads, heat fluxes, or mass transfer onto nearby discrete elements while maintaining global conservation of flux quantities. This new numerical formulation allows for integration of the various partitioned domains and ensures consistent data transfer between them. The framework is tested on various geometries, and surface containment errors below 2.5% and flux-transfer errors below 1% are obtained. Transient simulations of uniform surface recession further confirm accuracy in coupled evolution, with predicted volume loss agreeing with analytical solutions to within 1%. The proposed method establishes a general and extensible framework for consistent interface reconstruction and coupling in multiphysics environments, providing a pathway toward unified treatment of discrete-continuum interactions for a wide range of systems.