Pedestrian-level wind and gust around buildings with a ‘lift-up’ design: Assessment of influence from surrounding buildings by adopting LES

An architectural feature, ‘lift-up’ (or elevated) design, has been reported as an effective design to improve weak pedestrian-level wind (PLW) conditions in a subtropical high-density city. This design provides a semi-outdoor space under the elevated building which allows wind to penetrate through, but the influence of surrounding buildings on its performance has been rarely reported. This study aims to assess the influence of surrounding buildings on the PLW around an elevated building. LES (large eddy simulation) approach is applied after validation against the previous wind tunnel tests. Validation studies have confirmed and proven the accuracy of LES for the simulations, with the correlation coefficients R above 0.89 between the predictions and the experiments. Furthermore, the differences of flow fields are assessed around a single elevated building and a building array with an open space, a building and an elevated building respectively in the centre. Results indicate that wind amplification exists within the semi-outdoor space under the elevated building in all conditions although this effect is partially lowered by the surrounding buildings. The fields of turbulence intensity and gust wind speed around the surrounded elevated building are investigated by LES. These findings can be helpful for using the ‘lift-up’ design to improve wind and thermal comfort at pedestrian level.