Large-scale fluid network analysis: mixed pressure and flow specifications

Most pipeline network problems can be solved by the orthogonal transformation approaches — the mesh and nodal methods. However, when the network size becomes too large, the mesh and nodal approaches may not be suitable. Under such circumstances, the mesh diakoptics and nodal diakoptics methods can be used. The diakoptics approaches are nevertheless subjected to a constraint, which is all the flows of the network have to be specified. If a combination of flows and pressures is specified, these methods cannot be used. In the present work, a special technique called the fictitious branch method is employed to complement the diakoptics approaches to solve mixed specification problems. It is found that for an all pressure specified problem, it is better to use the nodal diakoptics approach. Otherwise, the mesh diakoptics approach is always preferred.