Advantages of Using the Multiphysics Interfaces

The Nonisothermal Flow and Conjugate Heat Transfer interfaces combine the heat equation with either laminar flow or turbulent flow and use either a , , or domain model. The advantage of using the multiphysics interfaces is that predefined couplings are available in both directions. In particular, physics interfaces use the same definition of the density, which can therefore be a function of both pressure and temperature. Solving this coupled system of equations usually requires numerical stabilization accounting for the couplings, which the predefined multiphysics interfaces also set up.

	When the flow Compressibility is set to Incompressible flow, the Nonisothermal Flow coupling follows the Boussinesq approximation and evaluates the thermal material properties at the reference temperature define in the heat transfer interface. Hence, the Phase Change Material domain model—which requires the temperature dependency of the heat capacity—should be used only with the Weakly compressible flow and Compressible flow (Ma<0.3) options.

When the flow is set to , the coupling follows the Boussinesq approximation and evaluates the thermal material properties at the reference temperature define in the heat transfer interface. Hence, the domain model—which requires the temperature dependency of the heat capacity—should be used only with the and options.

	When the Nonisothermal Flow and Conjugate Heat Transfer interfaces couple a turbulent flow with a Phase Change Material domain model, it must be noted that only the geometry boundaries are considered for the definition of the wall functions and of the wall distance. For example, at the moving melting front between the solid and the liquid phase, no wall functions are used by the k-ε and k-ω turbulence models.

When the and interfaces couple a turbulent flow with a domain model, it must be noted that only the geometry boundaries are considered for the definition of the wall functions and of the wall distance. For example, at the moving melting front between the solid and the liquid phase, no wall functions are used by the k-ε and k-ω turbulence models.