Equivalence of pipes with distributed flow in pressurised pipe networks

In pressurised pipe network models, the flow exchange between the network and the external environment is schematised as taking place only at nodes. Consequently, in order to simulate distributed demands or diffused leakages a pipe must be divided in several segments, which requires introducing additional nodes corresponding to the flow exchange locations. Therefore, the resulting computational burden may significantly increase. Alternatively, a global and more efficient approach can be used where a single equivalent pipe element yielding the flow and the same values of pressure at the ending nodes can be used, provided that an appropriate definition of the equivalence is guaranteed. This equivalence requires that the two approaches (lumped and distributed) give the same results in terms of pressure heads at nodes and flows in pipes when a numerical simulation model is used. In other words, two pipes with lumped or distributed demand, will provide the same results in the hydraulic model, although alternative governing equations, different from the classical Bernoulli equation, will be used in order to compensate the difference in schematisation. © 2010 Taylor & Francis Group, London.