Consistent inflow turbulence generator for LES evaluation of wind-induced responses for tall buildings

A new turbulent inflow generator technique that can be used as inflow boundary condition for LES of lower atmospheric boundary flow (ABL) is proposed based on synthesizing random divergent-free turbulent velocities. The proposed technique distinctively maintains both the turbulent spectra and coherency function similar with the target ABL flow, which is essential for proper simulation of interaction of turbulent ABL flow with flexible structures prone to wind-induced dynamic excitation. The accuracy of the proposed technique to produce turbulent velocities with proper spectra and coherency function is assessed in comparison with typical ABL flow characteristics obtained from the literature. Further, its appropriateness to evaluate wind-induced response for tall building is assessed by employing the proposed technique as inlet boundary condition for LES of the ABL flow around a tall building that was previously tested in a boundary layer wind tunnel. Comparison between dynamic responses (acceleration) and base load spectra (along-wind, across-wind and torsional) acquired from the proposed LES with those from the boundary layer wind tunnel shows a very good agreement. Thus, confirming the suitability of the proposed technique for evaluating wind-induced responses. Moreover, the proposed technique is computationally effective and easily amendable for parallel computing making it useful for generating consistent inflow turbulence while adopting LES for wider wind engineering applications.