Here is an example of a hydraulic study carried out by EIF-services. A few days work allowed to reach relevant results without resorting to high performance computing. It was of matter of calculating the capacity of a storm water drainage system. The relatively simple network consisted in four pipes of various lengths and slopes, some of which connected in series, others in parallel. This type of flow is classically described by the Colebrook formula (drawn in the famous Moody diagram) and thus one just needed to develop an ad hoc spreadsheet, illustrated by the screenshot below.
The algorithm is detailed in the Fluid Mechanics by Franck M. White (2016) and allows one to model the whole system of pipes and junctions thanks to an iterative procedure, taking into account minor head losses.
The results were validated against DTU 60.11 "Calculation rules for plumbing and storm water installations" (2013) in the particular case of a single partially filled pipe (as exemplified above).