Speaker: Irina Afanasyeva, University of Arkansas | Department of Mathematical Sciences
Date: Wednesday, October 4, 2023, 4:00 – 5:00 PM
Location: Science Engineering Hall (SCEN 408)
Title: Examining the Effects of Synthetically Generated Inlet Turbulence on Wind Loads using Large Eddy Simulation (LES)
Abstract: Precise prediction of peak wind pressures on buildings, especially for low-rise ones, is still challenging for wind engineers. For the most used experimental approach to determine wind loads like Wind Tunnel (WT) testing there is a scaling issue of reproducing highly turbulent flow accurately in the near-ground boundary layer where the low-rise buildings are immersed. Also, studies show that WT lacks energy in low-frequency regions of the wind spectrum which causes severe underestimation in peak pressures. An alternative and complementary approach to WT testing is Computational Fluid Dynamics (CFD). CFD helps to model turbulent flow reasonably accurately if the Large Eddy Simulation (LES) approach is used with proper inflow turbulence. Existing inflow turbulence generators (ITGs) are sensitive to the given input parameters to obtain desirable wind spectrum like von-Karman spectrum at the inlet. If the high frequencies greater than those which LES can resolve are present in the inflow spurious unrealistic pressures occur. Also, ITGs lose their energy while approaching the building location compared to what is generated at the input. This study concentrates on applying Synthetic Eddy Methods to enhance peak pressure predictions on building envelopes. It delves into understanding the impact of synthetically generated turbulence introduced at the inlet on wind loads. This is achieved by comparing CFD results across models with varying grid resolutions (coarse, medium, fine) under different conditions: with and without turbulent inflow, in conjunction with WT data. The outcomes reveal the influence of introduced turbulence at the inflow on mean and peak pressures, as well as on the frequency characteristics of wind loads. Finally, the study evaluates the performance of different ITGs based on criteria such as wind load magnitude, pressure frequency content, and the structure of turbulent flows.
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