Comprehensive adaptive modelling of 1-D unsteady pipe network hydraulics

Abstract

Multiple types of 1-D flow models simulate unsteady pipe network hydraulics. Water hammer models capture highly transient hydraulics, whereas incompressible flow formulations are more computationally efficient. Recent efforts to balance the accuracy–efficiency tension have been limited by numerical instability, model applicability, and inefficient solution schemes. Here, a novel adaptive hybrid transient model (AHTM) is presented that efficiently simulates the full range of unsteady flow conditions. The methodology combines the comprehensive global gradient algorithm (CGGA), a unique solver, with unsteady flow characterization indices and an adaptive scheme. Water hammer, rigid water column, and quasi-steady models are generalized to the CGGA within a unified framework; together with an adaptive scheme, the AHTM automatically adjusts the CGGA. Accordingly, dynamic effects are only simulated when present using an appropriately small time step. From two examples, the AHTM is shown to permit accurate and efficient simulations. Moreover, the framework is flexible and can be tailored to individual analyses.