Assessment of smoothed particle hydrodynamics methods for simulating the external-flooding scenario

Smoothed Particle Hydrodynamics (SPH), as a Lagrangian mesh-free method, is one of the particle-based Computational Fluid Dynamics (CFD) methods. Because of the unique capability of SPH in effectively handling large-scale fluid simulations with complex interfacial structures, SPH methods have been used as the CFD tool for simulating the generation, propagation, and interaction of flooding with Nuclear Power Plants (NPPs). However, the previous study assumes that SPH methods and the corresponding simulation packages are applicable to the external-hazards risk analysis, and simulation uncertainties do not affect the confidence of safety decision. Since the risk analysis aims to inform and support the decision-making regarding the design, operation, and safety of NPP, where uncertainties have high consequences, a systematic and consistent validation process is needed to evaluate the adequacy of SPH simulations. In this study, an initial assessment is performed for systematically evaluating the SPH’s adequacy in simulating the external flooding. First, an external-flooding scenario is designed, and SPH simulations are performed with an SPH-based software named Neutrino. Since validation databases are collected from literature, only one of the high-ranked phenomena in the designed scenario is investigated. In this study, the phenomenon “hydrodynamic force on stationary structures is selected”, and the dam break is used as one of the numerical benchmarks for assessing the performance of SPH methods and Neutrino. At the same time, a code performance standard is created for measuring the adequacy consistently and transparently. Next, code assessments are performed by comparing simulation results from Neutrino against experimental measurements. Meanwhile, a scaling analysis is performed to identify the applicability of collected validation database in the reduced-scale facility to the prototypic scenario. Finally, results are collected from all activities, and an adequacy decision is made accordingly. And it is found that with given validation databases and suggested particle sizes, SPH methods and its software package Neutrino can predict the hydrodynamic force on stationary structures with reasonable performance.