Simulation of approaching boundary layer flow and wind loads on high-rise buildings by wall-modeled LES

Abstract

This study presents a simulation framework of approaching boundary layer flow with appropriate characteristics by large-eddy simulation (LES), which is critically important for predictions of wind pressures and loads on buildings and other structures. The framework is consisted of spectral representation (synthesis) approach for inflow turbulence field generation and adjusting strategies to achieve appropriate approaching flow characteristics. The adjusting strategies include implementation of wall-stress model based on the equilibrium law of wall and adjusting of inflow turbulence parameters. The wall-stress model facilitates modeling of the effects of ground roughness without explicitly resolving the geometric roughness elements, also bypassing the prohibitive near-wall grid resolution requirement. The adjusting of inflow turbulence parameters, including correlation coefficient of inflow longitudinal and vertical fluctuating velocity components and amplification factor of inflow vertical fluctuation level, is proposed based on Reynolds stress budget to shorten the buffer region and to mitigate the decay of longitudinal turbulence intensity profile. To verify the proposed framework, the approaching flow corresponding to a wind tunnel test is firstly simulated and a comprehensive parametric study is conducted. With the adequately simulated turbulence field, the wind pressures and integrated loads on a high-rise building model are then simulated and compared with the wind tunnel test results. The results demonstrate effectiveness of the proposed wall-modeled LES framework for approaching flow simulation and wind loads assessment.