Efficient FSI solvers for multiple-degrees-of-freedom flow-induced vibration of a rigid body

Abstract

Flow-induced vibration (FIV) of a bluff body is a complex fluid-structure interaction (FSI) problem, for which analytical solutions generally don’t exist. Therefore, such problems generally need to be examined with experimental methods or computational simulations. Researchers have developed various numerical methodologies to solve FSI problems using either conforming or non-conforming grid methods. However, these methods are not always ideal for flow-induced vibration problems, as they can be computationally expensive or generate low accuracy solutions, especially for the cases with large body displacements. FIV problems often require long simulation times because, for a given parameter set, the transient flow solution time can be long and generally at least 10 oscillation cycles are required to simulate the representative long term behaviour. Thus, to gain a clear understanding and enhance knowledge of FIV of a bluff body, it is advantageous to have an efficient numerical methodology. We have developed two efficient fully-coupled FSI solvers to accurately predict the FIV of an elastically mounted bluff body and a tethered bluff body. These FSI solvers were developed based on the widely used open-source CFD package OpenFOAM. In these solvers, the fluid flow was modelled in a reference frame attached to the centre of mass of the solid body, so that a non-deforming grid can be employed. A predictor-corrector iterative method was used to enable strong coupling between the solid motion and the fluid flow. Each of the FSI solvers was validated against previously reported investigations. While efficient, the limitation of these FSI solvers is that they can only be used to examine the nature of FIV of a single, rigid bluff body.