Convergence/results problems in a model

Isaac

Hello.

We´re trying to model a 1-D flow in Phoenics 3.5.1. Model has sharp changes in flow sections (cylinders) and a flow in a ring pipe, but we're having a lot of problems of convergence and confusing results on pressure drop while changing the number of cells on domain.

We changed the default model equations (Elliptic-Staggered) to Elliptic-Colocated and the convergence problems seem to be solved but the confusing results remain.

Is it any other equation model that could improve the results quality? What are the differences among the models variants? (CCM, CCV, etc) I have taken a look on Phoenics help about the issue but I've found more academic-oriented than user-oriented.

Thanks in advance.