Decomposing the Unsteady Flow Routing in River Systems

Abstract:

This work presents an optimization-based domain decomposition strategy for unsteady flow

routing in complex river systems. This strategy couples the domain decomposition technique

with a Precomputed Channel Hydraulics Ensemble approach, known also as Hydraulic

Performance Graph (HPG), which utilizes precomputed solutions along reaches on a river

system. These solutions are stored in a database. While efficient and robust, HPGs requires

extensive memory allocation, especially for high resolution simulations. Decomposing the river

system into subdomains reduces computer memory constraints as each sub-domain is solved

independently. Further, an optimization method is used to couple the sub-domains using the

stored precomputed solution. In turn, the computational efficiency of the HPG approach allows

the optimization-based scheme to be competitive with a whole domain methodology. The

combined strategy is expected to reduce the overall computational time for large-scale problems.

This work discusses the results of the application to the Columbia River (Northwest USA).