Because of the increase of the computational power, the improvement of the programming languages, of the numerical methods and of the physical models, the complexity of the physical problems that can be studied by numerical simulation constantly increases. In particular, the ingineer demand turns towards the possibility to treat coupled problems. In that purpose, research and development actions are currently carried out in the Trio_U project and two issues are more particularly studied.
The first one deals with the coupling of physical models. In particular, in the study of the thermal-hydraulic behavior of nuclear reactors, it is important to study the couplings between a fluid region and a porous medium.
The second issue deals with the coupling between different computational codes. Indeed, some computational codes, like Trio_U, are more particularly dedicated to a local modeling of flows, whereas other codes, like Cathare, are optimized to solve problems at a much larger scale (they are called system codes). For some applications, it can be important to simulate the entire circuit with macroscopic models and to simulare more precisely a part of the circuit.