Inflow turbulence generation for LES of wind flow around bluff body

Large eddy simulation (LES) has been widely applied in wind-related problems. A key issue to ensure obtaining accurate results by LES is to generate an appropriate inflow field satisfying the physical wind characteristics in the atmospheric boundary layer (ABL). The methods adopted in this study for inflow field generation include two statistical methods (the random flow generation method (RFG) and the synchronizing random flow generation method (DSRFG) and a numerical method (the recycling method). These inflow generation methods are used to predict the wind effects on the Commonwealth Advisory Aeronautical Council (CAARC) standard tall building. The computational results show that all the three methods can reproduce the time-averaged velocity and turbulence intensity profiles quite well at the building position. However, the RFG method is incapable of generating fluctuating velocity satisfying the prescribed von Karman spectrum, and the DSRFG method yields random flow field satisfying the target spectrum at the inlet, while the recycling method generates the streamwise velocity fluctuation quite well at the inlet. The mean pressure coefficients on the front surface of the building are accurately predicted by all the inflow turbulence generators (the three methods), and the pressure coefficients distribution patterns on the side and back surfaces are well predicated, while some discrepancies still exit between the numerical results and wind tunnel measurements. All the RMS pressure coefficients obtained by the inflow turbulence generation methods fall in the range of wind tunnel data, illustrating that the effects of turbulence characteristics on the windinduced pressures on the tall building are reproduced to some extent.