Accurate CFD Modeling of Atmospheric Boundary Layer with an Emphasis on Wind-Induced Response of Buildings

当涉及到建筑物的风荷载评估时，设计规范有一些限制，这些限制可以通过风洞WT测试或计算流体动力学CFD模拟来克服。风洞测试通常需要很长的准备时间（几周或几个月）来构建模型和使用仪器，如果使用并行计算能力，则不需要CFD。正确地模拟大气边界层是准确进行CFD模拟的关键。本文重点评估并提高CFD中两种生成bl的方法（即分形表面粗糙度法和一致随机离散流生成CDRFG法）对高层建筑风致荷载及响应的评估精度。首先，选定的两种生成bl的方法将在RWDI常用的Ryerson U提供的ANSYS FLUENT和Open Foam软件上进行整合。然后，将进行多次模拟以找到参数（及其范围），从而使用空域精确模拟BLs。一旦这些参数（及其范围）被确定，模拟将扩展到包括有和没有周围配置的建筑物，以评估风诱导的载荷和响应，这将通过Ryerson和RWDI的WT实验进行验证。本研究项目的预期结果代表了两种使用CFD对湍流BLs进行精确建模的方法。这些方法将使RWDI能够以更低的成本更快地进行风力工程研究，同时保持准确性。这不仅对RWDI有很大的好处，而且对加拿大也有很大的好处，因为由此产生的方法最终将导致更有弹性的建筑物应对由气候变化引起的与风有关的灾害，这是加拿大政府的一个优先研究领域。

Design codes have several limitations when it comes to wind load evaluation of buildings, which can be overcome by using Wind Tunnel WT testing or Computational Fluid Dynamic CFD simulations. Wind Tunnel testing typically requires a long lead time (several weeks/months) for the model construction and instrumentation, which is not the case for CFD if the parallel computational power is utilized. It is essential for an accurate CFD simulations to properly model the atmospheric Boundary Layer (BL). This proposal focuses on assessing and enhancing the accuracy of two of BL-generating methods in CFD (namely the fractal surface roughness method and the Consistent Random Discrete Flow Generation CDRFG method) to evaluate wind-induced loads and responses of tall buildings. First the two selected BL-generating methods will be incorporated on ANSYS FLUENT and Open Foam software available at Ryerson U and commonly used by RWDI. Then, several simulations will be conducted to find the parameters (and their ranges) leading to accurate simulation of BLs using empty domains. Once those parameters (and their ranges) are identified, the simulations will be extended to include buildings with and without surrounding configurations to evaluate wind-induced loads and responses, which will be validated against WT experiments at Ryerson and RWDI. The anticipated outcomes of this research project represent two accurate modeling methods for turbulent BLs using CFD. Those methods will enable RWDI to conduct wind engineering studies faster, at a lower cost while maintaining the accuracy. This will be of a great benefit to not only to RWDI, but also to Canada as the resulting methods will ultimately lead to more resilient buildings to wind-related disasters frequently driven by the climate change, which is a priority research area for the Canadian Government.