Across-wind excitation mechanism for interference of twin tall buildings in staggered arrangement

This paper explores the excitation mechanism for across-wind force interference of two tall buildings in staggered arrangement through detailed measurement of turbulent flow fields past the two buildings and concurrent pressure measurement on the downstream principal building. Analysis of the instantaneous flow fields and wall pressure distributions reveals a synchronization process between the sideway oscillation of the upstream building wake with vortex development and shedding from the downstream principal building. Further analysis using the phase averaging technique confirms that the synchronization of five quasi-periodic aerodynamic phenomena is responsible for the magnification of across-wind force fluctuations in a region of building arrangements centered at a longitudinal building separation of 5 building breaths (D) and a lateral separation of 2.5D. In addition to this “wake interference region I”, three other flow regions of staggered arrangement are classified, namely, “wake interference region II” in which wake development on the principal building is affected by impingement of the meandering upstream building wake in a close lateral separation, “proximity interference region” which is characterized by channeled flow through a narrow gap between the two buildings, and “weak interference region”.