The wind field around a 1:1:2 isolated building was predicted by large-eddy simulation for evaluating the pedestrian-level wind environment. This study focused on the effects of cell types (hexahedral, tetrahedral and polyhedral cells) and boundary layer mesh on the time-averaged and fluctuating wind characteristics. The minimum cell size and stretching ratio were set to be the same among all cases. The case composed of hexahedral cells was found to have the best agreement with the experiment among the three cell types. The accuracies of the polyhedral cases are close to that of the hexahedral case, and better than those of the tetrahedral cases. However, the polyhedral mesh is most economical for the computational resources since the cell numbers of the polyhedral cases are less than half of that of the hexahedral case and about a quarter of those of the tetrahedral cases. It was also found that the boundary layer mesh does not improve the numerical accuracy under any circumstances. For both tetrahedral and polyhedral meshes, the boundary layer mesh can improve the numerical accuracy in the region above the flat ground by reducing the mesh non-orthogonality and skewness. However, the boundary layer mesh was found to worsen the mesh quality in the local region around the sharp corners of the building for both tetrahedral and polyhedral meshes. As a result, the boundary layer mesh did not lead to the expected improvement of numerical accuracy of wind velocity in the sensitive region of the separated flow from the sharp corners.

通过大涡模拟来预测1：1：2隔离建筑物周围的风场，以评估行人水平的风环境。这项研究集中在单元类型（六面体，四面体和多面体单元）和边界层网格对时间平均和波动风特征的影响上。在所有情况下，最小像元大小和拉伸比均设置为相同。发现六面体细胞组成的情况与三种细胞类型中的实验最吻合。多面体情况的准确性接近六面体情况，并且优于四面体情况。然而，多面体网格对于计算资源而言是最经济的，因为多面体情况的单元数小于六面体情况的单元数的一半，而四面体情况的单元数的大约四分之一。还发现边界层网格在任何情况下都不能提高数值精度。对于四面体和多面体网格，边界层网格可以通过减少网格的非正交性和偏斜度来提高平坦地面上方区域中的数值精度。然而，对于四面体和多面体网格，发现边界层网格会恶化建筑物尖角周围局部区域的网格质量。因此，