Seismic Fluid-Structure Interaction in Tanks Using an Acoustic Formulation: A Verification and Validation Study

Due to its computational efficiency and an ability to model complex geometries, an acoustic fluid-structure interaction (FSI) formulation is an attractive numerical approach for modeling fluid-filled tanks. However, few large-scale verification and validation (V&V) studies exist that use acoustic FSI for seismic analysis while considering multiple response quantities and multi-directional seismic inputs. We present such a V&V study performed using the Multiphysics Object-Oriented Simulation Environment (MOOSE). We first verify the acoustic FSI formulation using simple benchmark problems for which exact analytical solutions are available. Next, we verify acoustic FSI for a head-supported cylindrical tank partially filled with water and subjected to uni-directional shaking by comparing with analytical solutions, with which, the acoustic FSI results match closely. We validate acoustic FSI by comparing the simulation results with experimental data considering multi-directional seismic shaking of a base-supported cylindrical tank partially filled with water and subjected to peak ground accelerations of 0.1-1g. The acoustic FSI implementation in MOOSE satisfactorily predicts peak pressures and support moments recorded during the experiments. The comparisons also show that it might be challenging to predict the wave height at the fluid surface, given the complex surface wave responses, especially at more intense shaking. A comparison of simulation times showed that acoustic FSI is at least an order of magnitude faster than the arbitrary Lagrangian-Eulerian and incompressible computational fluid dynamics numerical methods. To demonstrate MOOSE's capabilities for handling large multiphysics numerical models , seismic FSI analysis is performed on a full-scale nuclear power plant building that houses a molten-salt reactor vessel.