Computational Prediction of Wind Induced Virations in Silo Groups Using 2d and 3d Cfd Simulations

Wind induced ovalling vibrations were observed during a storm in October 2002 on several empty silos of a closely spaced group consisting of 8 by 5 thin-walled silos in the port of Antwerp (Belgium). To clarify the cause and location of the observed silo vibrations, a thorough analysis of the aerodynamic pressures on the silo surfaces is required. Therefore, both 2D and 3D computational fluid dynamics (CFD) simulations have been performed. While the 2D simulations mainly aim at studying the influence of the angle of incidence of the wind flow on the location where ovalling vibrations can be observed, the 3D simulations are performed to incorporate 3D flow effects into the analysis and to assess the validity of the conclusions of the 2D simulations. The 3D pressure distribution on the silo walls is applied as an external time dependent load on a 3D finite element model of a silo to determine the structural response. Afterwards, modal projection of the load is performed to determine the contribution of each ovalling mode shape to the dynamic structural response. For the 2D simulations, a similar technique of harmonic decomposition is derived and validated with the 3D one-way coupling approach. The results of both approaches yield evidence of the onset of ovalling vibrations, corresponding to the observed pattern of oscillations in the Antwerp silo group.