MSc thesis seminar by Clément Chigot with the title: "Numerical simulation of fixed and vibrating cylinders in a cross-flow"

Abstract:

"As the consequences of tube vibrations in nuclear reactors can be critical, numerical simulation tools
are very useful to better understand and predict these fluid-structure interaction (FSI) phenomena. In
this study, an FSI coupling is implemented in the CFD software STAR-CCM+, in order to simulate
vibrations of cylinders in a cross-flow. Firstly, the flow around a fixed and rigid cylinder with a Reynolds
number of 3900 is simulated. CFD calculation rules are established and several turbulence models are
tested, including the STRUCT-ε, a 2nd generation URANS turbulence model. Overall, the mean velocity
profiles, as well as the mean drag coefficient and the root mean square of the lift coefficient obtained
with the STRUCT-ε model are closer to the experimental results than the other 1st generation URANS
models tested. Secondly, this STRUCT-ε model, coupled to a solid solver via a two way implicit coupling,
is used to study the fluid-structure interactions for two inline cylinders in a cross-flow with a Reynolds
number around 4000. The simulation parameters are chosen to reproduce an FSI experiment intended
for the study of tube vibrations and conducted by OKBM. In this experiment, the two cylinders have
different natural frequencies, one is therefore subject to vortex-induced vibrations (VIV) and the other,
in its wake, to turbulence-induced vibrations. Mean velocity profiles are in good agreement with
experiments, while differences are observed for the acceleration spectra, especially for the first
cylinder. From these results, avenues for improving the calculation scheme are proposed."