RESEARCH ON AN IMPROVED INFLOW TURBULENCE GENERATION APPROACH FOR LARGE EDDY SIMULATION

Abstract

The inflow turbulence generation technique in the large eddy simulation (LES) research is a hot topic in the field of computational wind engineering. Based on the narrowband synthesis random flow generation (NSRFG) approach, the quantitative relationship between the tuning factor \begin{document}${\gamma _j}$\end{document} and the dimensionless length scale \begin{document}$\beta $\end{document} is theoretically derived through deep investigation of several important parameters, i.e., the dimensionless length scale \begin{document}$\beta $\end{document} , the spatial correlation \begin{document}$R$\end{document} , and the tuning factor \begin{document}${\gamma _j}$\end{document} . An improved inflow turbulence generation technique, namely the improved NSRFG (INSRFG) method, is subsequently proposed. The LES simulations of turbulent wind fields corresponding to four typical standard wind terrains defined in the code are carried out by utilizing this method. The numerical comparison shows its applicability and accuracy in simulating the turbulent atmospheric boundary layer (ABL) flows, which satisfy the requirements of the fluctuating wind characteristics, such as the wind speed spectrum and the spatial correlation, and successfully achieve the equilibrium status for the numerical simulation of the ABL flow. The systematic study in this work shows that the proposed INSRFG technique has the advantages of clear parameter definition, compact mathematical expression and relatively high calculation efficiency, and has the potential to become a general inflow turbulence generator for large eddy simulations of building structures.