Pedestrian-level gust wind flow and comfort around a building array–Influencing assessment on the pocket park

• Wind flows around a building array and a row of trees are simulated and validated. • Mean and gust flow fields around building arrays with pocket parks are analyzed. • Pocket park amplifies PLW velocities under perpendicular inflow wind. • Pocket park promotes PLW comfort for sitting under oblique and parallel winds. Congested urban forms deteriorate urban ventilation, causing the problem of poor wind comfort at the pedestrian level. Pocket parks are small-scale open spaces for neighborhoods’ recreations, and they have the potential to alleviate this problem in cities, while this is rarely quantitatively investigated. This study investigates the pedestrian-level wind (PLW) flows around building arrays, and the influences of pocket park and vegetation on the mean and gust wind flows, and the wind comfort are further assessed. Steady-state Reynolds Averaged Navier-Stokes (RANS) simulations with the RNG k-ε model are used and validated with the benchmark experiments that give correlation coefficients above 0.80, including winds around a building array and trees. Results indicate that pocket park amplifies the mean and the gust flows in the streets under the perpendicular inflow wind, while attenuates the flows under the oblique and the parallel inflow winds. Inside the pocket park, an outdoor shelter space is created for pedestrian to relax and gather when winds in the streets are overly high. In this case, the vegetation promotes wind comfort for short-term sitting. These findings provide evidence for quantifying the effect of pocket parks with and without vegetation in achieving a healthy outdoor open space.