Cross Comparisons of CFD Prediction for Wind Environment at Pedestrian Level around Buildings Part 1 Comparison of Results for Flow-field around a High-rise Building Located in Surrounding City Blocks

CFD is being increasingly applied to the prediction of the wind environment around high-rise buildings. However, the prediction accuracy and many factors that might affect simulation results are not yet thoroughly understood. In order to clarify ambiguities and to provide a guideline for CFD prediction of the wind environment, a working group was organized by the Architectural Institute of Japan. This group has carried out various comparative studies as follows. ・First stage: Flowfields around two types of single high-rise buildings. ・Second stage: Flowfield around a high-rise building located in a city. ・Last stage: Flowfields around two types of Building Complexes in actual urban areas. This paper describes the cross comparison results of the second stage. A high-rise building(25 ×25×100m) is surrounded by low-rise city blocks(40×40×10m). Wind tunnel experiments in a boundary layer using split-film probe were carried out by the present authors to obtain data for assessing the accuracy of CFD results. In the CFD simulations, the influence on prediction accuracy of calculation conditions such as boundary condition for ground surface, size of side and upper calculation region, grid system, range of surrounding city blocks, and turbulence models were investigated, and are discussed in detail.