Development of Numerical Wind Tunnel Concerned with Wind Engineering

本研究的目的是发展一个能精确预测建筑物周围紊流流场的数值风洞。数值风洞主要由两部分组成。一个是建筑物湍流流场数值预报系统。二是利用计算机图形系统对模拟结果进行可视化。1.建筑物周围气流的数值预测建筑物周围气流的数值模拟结果受多种因素的影响。因此，需要诊断系统来检查数值模拟的准确性。采用大涡模拟（Large Eddy Simulation）和k-模型（k- model）等湍流模型进行了数值模拟<epsilon>，分析了有限差分格式、边界条件和网格划分对模拟结果的影响。这些模拟的准确性进行了检查，通过比较预测结果与风洞实验作者进行。2.流动可视化系统，通过计算机图形时间精确的数值方法有能力冻结在任何时刻的流动，并立即产生速度，压力，和各种湍流统计的整个流场周围的建筑物。应用先进的计算机图形技术是消化计算机产生的大量数据的最合理的手段。我们使用Apollo Domain DN 550工作站开发了计算机图形系统。这个图形系统不仅允许解释的细节的数值生成的流场，但也允许进行比较之间的数值解和可视化表示的实际流动。

The purpose of this study is to develop the numerical wind tunnel which can predict turbulent flowfield around buildings precisely. The numerical wind tunnel consists of main two parts. One is the system for numerical prediction of turbulent flowfield around buildings. The other is the Computer Graphics System to visualize simulated results.1.Numerical prediction of air flow around buildingsResults of numerical simulation of air flow around buildings are supposed to be affected by many factors. So, the diagnostic system is needed for examining the accuracy of numerical simulations. Several types of numerical simulation by means of turbulent models, such as Large Eddy Simulation and the k- <epsilon> model are carried out to estimate the influences on simulated results of finite difference scheme, boundary conditions and mesh dividing system. The accuracy of these simulations is examined by comparing the predicted results with wind tunnel experiments conducted by authors.2.Flow visualization system by means of Computer GraphicsTime-accurate numerical methods have the ability to freeze the flow at any moment in time and to immediately yield velocities,pressures, and various turbulence statistics for the entire flowfield around buildings. The application of advanced computer graphics techniques is the most reasonable means by which to assimilate the massiveamounts of data generated by computers. We developed the Computer Graphics system using the work station Apollo Domain DN550. This graphics system not only allow interpretation of the details of the numerically generated flowfield but also allow comparisons to be made between numerical solutions and visualized representations of actual flow.