Scale Effects: Enhancing Wind Load Assessment on Structures

In the realm of boundary layer wind tunnels, investigations of large civil engineering structures typically employ geometric scales ranging from 1:500 to 1:100. However, scaling down aerodynamic models of smaller structures to such proportions presents two significant technical challenges. Firstly, the resolution of pressure data on these reduced models becomes inadequate. Secondly, these models may exist in the lower section of the boundary layer, failing to accurately replicate real-world scenarios due to the high uncertainty in wind velocity. To tackle these challenges, the development of a standardized testing protocol that accounts for both time and geometric scales becomes imperative for accurately assessing wind loads on structures.

Our research delves into the systematic examination of the sensitivity of wind loads on structures, employing both experimental wind testing and numerical computational fluid dynamics (CFD) techniques at varying geometric scales. The comprehensive results shed light on the impact of model size on wind load characteristics. While mean loads remain relatively unaffected by model size, peak loads display sensitivity to the geometric scale and spectral content of the test flow (turbulence), as well as Reynolds number. Importantly, we discovered that larger scales demonstrate feasibility in predicting peak loads, offering valuable insights for wind load assessments.

Our findings challenge existing guidelines by highlighting the influence of test building location on pressure correlation and the replication of peak loads. Additionally, we observed that the proximity of the inflow boundary plays a crucial role in accurately simulating wind conditions. The results obtained through CFD large-eddy simulation (LES) align closely with corresponding pressures from the open jet and full-scale data for roof component and cladding design. Furthermore, the CFD LES methodology showcases its prowess in generating peak pressures and loads on buildings that closely match field measurements. This capability stems from its capacity to reproduce the spectral content of the inflow at a 1:1 scale.

Our research signifies a significant step towards enhancing wind load assessment methodologies for structures. By considering the intricate interplay between time and geometric scales, we provide valuable insights into the sensitivity of wind loads, guide the selection of appropriate test locations, and highlight the effectiveness of CFD LES in accurately reproducing real-world conditions. These findings pave the way for improved design guidelines and code provisions, ensuring the resilience and safety of structures in the face of windstorms and other environmental challenges.


Scale Effects



Selected Publications