| When elastic cylinders are subjected to an axial flow, they will vibrate due to the loading imposed on the structure by the flow. This vibration is called axial-flow-induced vibration, which can wear the fuel rods in nuclear industry and make the cladding so thin that the radioactive material may be released. Thus it is necessary in engineering to study this vibration. In this project, the numerical simulation is carried out to study the fluid-structure interaction for elastic cylinders subjected to axial flow. The fluid and structure solvers are coupled together by an explicit partitioned scheme.;The dynamics of a single cylinder, which is subjected to axial flow and is limited to vibrate only in one plane, is studied. When the flow is laminar, the vibration of the cylinder is always damped by the flow for current dimensionless flow velocities and the damping increases with increasing the dimensionless flow velocity. For turbulent flow, when the dimensionless flow velocity is lower, the strong vibration of the cylinder is damped into weak vibration. However, the vibration becomes instable and the cylinder is eventually buckled if the dimensionless flow velocity is large enough.;Secondly, the dynamics of a cylinder, however, which can be free to vibrate in any transverse directions in axial turbulent flow, is studied. The dynamics of the cylinder is similar to that when it is constrained to vibrate in one direction. However, the flutter instability is captured as well as the buckling instability.;The dynamics of two simple clusters consisting of respectively two and four cylinders is also studied. The cylinders are free to vibrate in any directions. At small dimensionless flow velocity, the damping of the flow on strong vibration is also captured. When the dimensionless flow velocity becomes large enough, the buckling instability can be captured.;The current results are qualitatively consistent with the available experiments and theoretical analyses, and they could capture the features of fluid-structure interaction in detail. The numerical methods applied in this project can be used to predict the vibrations of the rods in nuclear industry. |
