The skeletonization of Milan WDS on transients due to pumping switching off: preliminary results

This paper is an extension of a previous paper (Brunone et al., 2013), in which a transient test procedure is discussed on the basis of field tests executed in the steel water distribution system (WDS) of Novara in the northwestern part of Milan, Italy, managed by Metropolitana Milanese S.p.A. In this paper, tests are repeated by modifying test conditions and improving the successive analysis. In particular, since the pump switching off is slow and unmodifiable, some of the main connections reached by the pressure waves before the end of the maneuver have been closed during the test. In such a way, the interference between the maneuver and the system has been reduced. The wavelet transform (WT) is used to evaluate the pressure wave speed of the supply pipe. In order to estimate the other pressure wave speeds, an optimization procedure is carried out. First of all, a skeletonization of the network is operated and then a Lagrangian model (LM) and a Genetic Algorithm (GA) are coupled considering such a skeletonized sys- tem. By minimizing the difference between numerical and experimental pressure signals, the optimal values of the pressure wave speeds are obtained. Finally the procedure is checked by comparing the experimental pressure signal and the one obtained by LM considering the optimal values of the pressure wave speeds and the actual network