Simulation of flexible slender 1-D structures using open-source software OpenFOAM for marine offshore applications

Authors: Seevani Bali, Zeljko Tukovic, Philip Cardiff, Alojz Ivankovic, Vikram Pakrashi

This work presents the formulation of flexible slender 1-D structures using a finite volume numerical approach in an open-source computational software, OpenFOAM. The motivation behind such implementation is to provide insights into the fluid-structure interaction of underwater sea cables/mooring lines with oceanic waves using a single numerical framework and to investigate the impact of underwater cables on the stability of offshore floating structures. The statics and dynamic formulation of such flexible cables are analysed using a nonlinear Simo-Reissner rod theory, which can model large deformations and finite rotations. A cell-centred, total Lagrangian finite volume spatial discretisation scheme and a Newmark-beta implicit time integration methods are used to model such flexible cables’ static and inertial contributions. The accuracy of the proposed methodology is presented by comparing the simulated numerical results with classic static and dynamic benchmark test cases available in the literature that are solved using finite element techniques. Additionally, contact algorithms are also developed to model multiple interactions of the individual cables within their elemental structure. A frictionless point-to-point and line-to-line contact formulations, developed in finite element literature, are adapted towards finite volume framework and benchmark test cases are numerically simulated to establish the efficacy of the proposed algorithms. The research received funding from Science Foundation Ireland MaREI project RC2302_2, Science Foundation Ireland NexSys 21/SPP/3756 and industrial partner Bekaert for this work is gratefully acknowledged.