The present study used large eddy simulations (LES) to examine the pedestrian wind velocity distribution for several cases of terraced houses with extensions. Two simulation cases of idealized terraced houses were performed with extension elements in square (E-SQ) and staggered (E-ST) arrangements. These extension elements were treated as secondary roughness. A simulation of the terraced houses without extension (NE) was also performed to provide a baseline comparison. The mean velocity distribution from LES showed that the secondary roughness strictly limited the flow penetration in both cases, which reduced the turbulent kinetic energy (TKE) inside the canyon. In comparison, E-ST had a stronger effect on TKE than E-SQ with a maximum difference of 19%. Downwind extension elements severely reduced the wind speed at the street and neighbors’ houses by about 40% to 50%. However, upwind extension elements increased the wind speed at neighbors’ houses about threefold compared to NE. The weak pedestrian wind speed at upwind houses was improved about twelve times with E-SQ and eight times with E-ST when neighbors extended their houses. This indicates that the secondary roughness significantly influences the wind distribution around buildings. Selecting the extension area is important for providing effective outdoor flow conditions.

本研究使用大型涡流模拟（LES）来检查几例带有扩展的排屋的行人风速分布。使用正方形（E-SQ）和交错（E-ST）布置的扩展元素进行了理想露台房屋的两个模拟案例。这些延伸元件被视为二次粗糙度。还对无扩展的梯田房屋（NE）进行了仿真，以提供基线比较。LES的平均速度分布表明，在这两种情况下，次生粗糙度都严格限制了流体的渗透，这降低了峡谷内部的湍动能（TKE）。相比之下，E-ST对TKE的影响比E-SQ强，最大相差19％。顺风扩展元素严重降低了街道和邻居房屋的风速约40％至50％。但是，上风向扩展元件使邻居房屋的风速增加了大约三倍。当邻居扩展房屋时，上风房屋的弱行人风速通过E-SQ改善了约12倍，而通过E-ST改善了8倍。这表明次要粗糙度显着影响建筑物周围的风分布。选择扩展区域对于提供有效的室外流量条件很重要。当邻居扩展房屋时，上风房屋的弱行人风速通过E-SQ改善了约十二倍，而在E-ST中改善了八倍。这表明次要粗糙度显着影响建筑物周围的风分布。选择扩展区域对于提供有效的室外流量条件很重要。当邻居扩展房屋时，上风房屋的弱行人风速通过E-SQ改善了约十二倍，而在E-ST中改善了八倍。这表明次要粗糙度显着影响建筑物周围的风分布。选择扩展区域对于提供有效的室外流量条件很重要。