An advanced numerical framework for the simulation of flow induced vibration for nuclear applications

In this work, an advanced solver for the simulation of Fluid-Structure Interaction (FSI) problems for nuclear applications is presented. The numerical framework, called as NRG-FSIFOAM, uses a Finite Volume (FV) fluid solver and a Finite Element (FE) structural solver coupled together with a partitioned approach. State-of-the-art implicit coupling algorithms are used in order to increase the accuracy and the stability of the solver for low solid-to-fluid density ratio, i.e. strongly coupled, FSI problems. Furthermore, the solver offers significant advantages with respect to traditional approaches for the solution of turbulent flows because it is equipped with an advanced algorithm to predict pressure fluctuations without the necessity to perform high fidelity simulations. This approach, called as Pressure Fluctuation Model (PFM), uses a stochastic model to generate velocity fluctuations that satisfy the mean turbulent quantities; the corresponding fluctuating pressure field is computed from the Poisson's equation. The pressure fluctuation field complements the mean pressure field computed with URANS models and it is then used as a part of the external forcing for the structural problem. This solver is first tested against benchmark FSI problems with laminar flows. Subsequently, it is used to simulate flow induced vibrations of cylindrical fuel rods in turbulent water and liquid metal flows and to simulate the vibrations of a cantilever beam in turbulent water flow.