A conservative fluid mechanics-heat diffusion solver coupling method is presented. Optimal use of solvers can be achieved by coupling according to a cycle time step
independent of classical numerical stability conditions. Solvers integrate their domains independently during a cycle. Between cycles, data are exchanged to compute a coupling boundary condition, which is imposed at the interface between the coupled domains. Conservativity is one of the main purposes of this coupling method. Consequently, Finite Volume method is used for the solvers. But during independent integrations by solvers, thermal flux losses happen at the interfaces between coupled domains. Conservative corrections are defined and used in order to maintain conservativity. But they can destabilize time integration. Stability criteria are established in order to achieve a robust conservative coupling, that eventually also improves integration accuracy
