High fidelity mathematical and computer modeling of coupled multiphysics problems require solutions to large systems of stiff, nonlinear, coupled equations. ‚Black-box‚ coupling strategies introduce several sources of error in the solution fields stemming from inaccurate and in some cases inconsistent treatment of the spatio-temporal nonlinear coupling terms. Choosing the right software and algorithmic options to resolve the inaccuracies are usually physics and problem dependent and hence a multiphysics framework needs to encompass several coupling schemes with varying stability and accuracy traits to solve dependent systems in order to analyze, compare and choose an optimal strategy. The schemes for solving the coupled systems are similar in principle for most approaches and with reusable design principles, accurate resolution of the spatio-temporal scales are possible. Different methodologies and the relevant numerics that are commonly employed for bringing together various physics components will be explored.

Finally, details of a coupling framework in development based on PETSc and MOAB libraries, CouPE (Coupled Physics Environment), for driving existing high-fidelity validated physics codes will be provided whose design aims to obtain tightly-coupled physical solutions by employing loosely-coupled software interfaces. Some relevant results obtained from nuclear engineering and radiation-diffusion problems with CouPE will be shown. The talk will conclude with proposed enhancements to such a glass-box framework to make it amenable to couple both existing and new physics solvers.