COUPLING OF MULTIPHASE FLOW MODELS

When modelling and simulating complex systems, one often needs to use specific models for each component to take into account their behavior. This is the case, for instance, for the modelling of the coolant flow in a Pressurized Water Reactor. In the frame of the NEPTUNE project, it is clear that to obtain a complete and coherent description of the system as a whole, one needs to couple these different models. We thus consider two separate domains sharing an interface. In each one, a different model is used to describe the flow. We want to single out the information to be transmitted through the interface in a way to obtain a coherent description of the unsteady flow. As an example, we consider a one-dimensional flow described everywhere by the same set of equations. An interface separates a region where the fluid is described by a given EOS and another region with a different EOS. This is a very common case in practice, since the tabulated thermodynamic functions used by different codes present some discrepancies. We compare different coupling schemes, originated from two distinct and relevant modelling choices and we show that they can lead to different solutions.