An optimized inflow turbulence generator for LES of wind effects on high-rise buildings using MINSRFG method

An accurate inlet boundary condition that captures the characteristics of the atmospheric boundary layer (ABL) is critical for large eddy simulations (LES) of high-rise buildings. This study proposes an optimized inflow turbulence generator—termed the Modified Improved Narrowband Synthesis Random Flow Generation (Modified Improved NSRFG, MINSRFG)—which combines the strengths of the Improved NSRFG (INSRFG) and the Modified NSRFG (MNSRFG) methods. The MINSRFG introduces a spectral energy correction coefficient α i and a time parameter τ 0 , along with an analytical expression for the spatial coherence adjustment coefficients γ j , thereby avoiding extensive trial-and-error in parameter selection. It enhances spatial coherence, improves temporal correlation, and compensates for the spectral energy loss in INSRFG, while addressing the difficulty of selecting spatial coherence parameters in MNSRFG. First, the method was numerically validated in a representative turbulent ABL flow field. The results show that the turbulence generated by MINSRFG accurately reproduces key turbulence statistics, including the fluctuating wind speed power spectrum, spatial coherence, and temporal correlation. Subsequently, MINSRFG, INSRFG, and MNSRFG were applied to three-dimensional LES of wind effects on the Commonwealth Advisory Aeronautical Research Council (CAARC) standard high-rise building model, and the results were compared with wind tunnel tests. Analysis of building surface pressure coefficients, base moment coefficients, and maximum top displacement indicates that MINSRFG outperforms the other two methods in both accuracy and error control for mean and fluctuating wind pressures as well as base moments. Under multiple wind directions, it also performs well in predicting building top displacement. In summary, MINSRFG offers clear parameter definitions and high computational accuracy, providing a high-precision inflow turbulence generation approach for LES of high-rise buildings.