A finite-volume approach for multi-branch junctions and its extension to FSI problems

A finite-volume approach is presented to tackle the junction problem of several branches at the same point in a one-dimensional framework. This approach is based on the integral form of the fluid governing equations at the junction which is considered as a three-dimensional fictitious cell connecting the different branches. Therefore, conservation of mass, momentum and total energy is ensured through the junction. What is more, the presented approach does not require the use of an iterative procedure and is independent of the Equation of State. In addition, thanks to its integral form, the present approach has also been extended to other more complex compressible two-phase flow modelling as the Baer-Nunziato-type model which involves non-conservative terms. The finite-volume junction method is then extended to fluid-structure interaction problems, i.e., the resultant fluid force at the junction is thus added as an external force for the beam elements coupled with the fluid governing equations. Assessment is finally performed on tests involving both pure fluid and coupled fluid-structure problems in conjunction with the junction of several branches.