Hybrid Simulator for Water Distribution Networks with Control Valves

This technical note presents a hybrid simulator designed for water distribution networks with control valves. The simulator is a modification of EPANET 2 that can handle valves using both the EPANET 2 heuristics and a recently proposed alternative method that models valves as pipes whose resistance is adjusted to meet the valve setting. The method copes with cases where the EPANET 2 heuristics fails, but it requires a larger number of iterations. The hybrid simulator starts with running the EPANET 2 heuristics and switches to the alternative method only if the former fails (cannot find a solution or produces incorrect results), thus using to advantage the fast convergence of the EPANET 2 heuristics and the more stable yet slower convergence of the alternative method. Verification tests demonstrated the ability of the hybrid simulator to deal with ill-posed problems and large networks with thousands of nodes, pipes, and valves.