The equation set required to support the energy sector is already represented as a multiphysics application. However, in some common cases of coupling including conjugate heat transfer and coupling to participating media radiation, an operator split method may be preferred. The general concept is to define multiple Nalu Realms that each own the mesh on which the particular physics is solved. Surface- and volume-based couplings are supported through linear interpolation of the coupling parameters.
A typical CHT application involves the coupling of a thermal response and fluid transport. The coupling occurs between the surface that shares the thermal equation and static enthalpy equation. Moreover, coupling to a PMR solve is a volume-based coupling. Multiple Realms are supported with multiple transfers.
In Nalu, the method to achieve coupling in CHT or RTE coupled systems is through the usage of the STK Transfer module. This allows for linear interpolation between disparate meshes. Advanced conservative transfers are being evaluated, however, are not yet implemented in the code base. In general, the STK Transfer interface allows for this design point.
For FSI, the usage of the transfer module is also expected.