A novel non-intrusive reduced order model (NIROM) for fluid–structure interaction (FSI) has been developed. The model is based on proper orthogonal decomposition (POD) and radial basis function (RBF) interpolation method. The method is independent of the governing equations, therefore, it does not require modifications to the source code. This is the first time that a NIROM was constructed for FSI phenomena using POD and RBF interpolation method. Another novelty of this work is the first implementation of the FSI NIROM under the framework of an unstructured mesh finite element multi-phase model (Fluidity) and a combined finite-discrete element method based solid model (Y2D). The capability of this new NIROM for FSI is numerically illustrated in three coupling simulations: a one-way coupling case (flow past a cylinder), a two-way coupling case (a free-falling cylinder in water) and a vortex-induced vibration of an elastic beam test case. It is shown that the FSI NIROM results in a large CPU time reduction by several orders of magnitude while the dominant details of the high fidelity model are captured. 
Non-intrusive reduced order modelling of fluid–structure interactions