Grid-free surface vorticity method applied to flow induced vibration of flexible cylinders

In order to study cross flow induced vibration of heat exchanger tube bundles, a new fluid-structure interaction model based on surface vorticity method is proposed. With this model, the vibration of a flexible cylinder is simulated at Re = 2.67 × 10⁴ , the computational results of the cylinder response, the fluid force, the vibration frequency, and the vorticity map are presented. The numerical results reproduce the amplitude-limiting and non-linear (lock-in) characteristics of flow-induced vibration. The maximum vibration amplitude as well as its corresponding lock-in frequency is in good agreement with experimental results. The amplitude of vibration can be as high as 0.88D for the case investigated. As vibration amplitude increases, the amplitude of the lift force also increases. With enhancement of vibration amplitude, the vortex pattern in the near wake changes significantly. This fluid-structure interaction model is further applied to simulate flow-induced vibration of two tandem cylinders and two side-by-side cylinders at similar Reynolds number. Promising and reasonable results and predictions are obtained. It is hopeful that with this relatively simple and computer time saving method, flow induced vibration of a large number of flexible tube bundles can be successfully simulated.