Abstract
This paper presents a GPU-accelerated, fully three-dimensional CFD–FSI simulation of vortex-induced vibrations (VIV) for a long flexible pipe representative of marine risers. Using the high-order spectral element solver NekRS coupled with a modal structural model, we simulate a 38m bare pipe with L/D = 1408 at Re ≈ 8100 and mass ratio m* = 1.62, matching a large-scale experiment performed in SINTEF Ocean’s ocean basin. The computed spanwise distributions of displacement standard deviation in both cross-flow and in-line directions show encouraging agreement with measurements, capturing nicely the dominant mode-shapes and the non-uniform response envelope along the span. Beyond validation, we quantify sectional fluid–structure energy exchange via. force–velocity correlation and identify a spanwise region local hydrodynamic damping in which the response is otherwise clearly excited, as a result of a globally traveling-wave response pattern. The results demonstrate the feasibility of GPU-accelerated high-fidelity CFD as a complement numerical tool to large-scale experiments and the potential of such a tool to provide in-depth physical understandings of the complex VIV problem of large aspect ratio flexible slender structures.