Coupling smoothed-particle hydrodynamics and torricelli's law-based hydraulic models for flooding risk analysis

Probabilistic risk assessments involving flood require accurate estimations of the time until critical equipment are reached by the water. Conventional approaches for assessing flooding risks employ a variety of simplifications on the water dynamics and geometries involved, limiting their accuracy and reliability. Conversely, 3-D fluid modeling methods make it possible to obtain exploitable data in the highest amount, variety and accuracy, but are associated with a significant computational cost and a limited spatial resolution. We present a hybrid approach, leveraging on the strengths of both previous approaches. An innovative and flexible coupling is realized between: a conventional hydraulic model, based on macroscopic balances and a generalized form of Torricelli's law; and a 3-D fluid model, solving the Navier-Stokes equations with smoothed-particle hydrodynamics. We demonstrate for an internal flooding scenario the benefits of this methodology, making use not only of several kinds of one-way coupling but for modeling flows under doors and through draining systems as well. It is able to provide a significantly more complete, accurate and reliable characterization of the flooding risks than the conventional methods, while keeping the computational trade-off at a moderate level.