A transport model of convective flow on self-excited vibrating flat flexible roofs using LES

This study aims to investigate the underlying mechanisms for the self-excited vibration of a one-way long-span flat roof. The large eddy simulations (LES) on both rigid and forced vibrating roofs with different vibrating frequencies are performed to obtain the aerodynamic forces and flow field data simultaneously. Firstly, the LES simulations on the rigid and vibrating roofs are validated against the reference experiments. Subsequently, the energy evolutionary characteristics of the aerodynamic forces on vibrating roofs are elucidated by the working energy analysis. Moreover, the interaction between the flow field and the vibrating roof is also revealed by flow visualizations, cross-correlation analysis, and spectral analysis. The synchronization between the transporting of vortices above the roof and the roof vibrations is qualitatively revealed and quantitatively confirmed at the occurrence of the self-excited vibration. Furthermore, a transport model of the convective flow is proposed and validated for the interaction between the vortex transporting and roof vibration. Ultimately, a semi-empirical function is established to predict the critical wind velocity of long-span roofs by modeling the vortex convection velocity in relation to the reduced wind velocity. The outcomes of this study will contribute to a deeper understanding of the flow mechanisms involved in self-excited vibrations of long-span roofs, ultimately informing the wind-resistant design of such structures in practical engineering applications.