Wake Characterization of Building Clusters Immersed in Deep Boundary Layers

Abstract Wind tunnel experiments were conducted to understand the effect of building array size ( N ), aspect ratio ( AR ), and the spacing between buildings ( $$W_S$$ W S ) on the mean structure and decay of their wakes. Arrays of size 3 $$\times $$ × 3, 4 $$\times $$ × 4,and 5 $$\times $$ × 5, AR = 4, 6, and 8, and $$W_S$$ W S = 0.5 $$W_B$$ W B , 1 $$W_B$$ W B , 2 $$W_B$$ W B and 4 $$W_B$$ W B (where $$W_B$$ W B is the building width) were considered. Three different wake regimes behind the building clusters were identified: near-, transition-, and far-wake regimes. The results suggest that the spatial extent of these wake regimes is governed by the overall array width ( $$W_A$$ W A ). The effects of individual buildings are observed to be dominant in the near-wake regime ( $$0 0 < x / W A < 0.45 ) where individual wakes appear behind each building. These wakes are observed to merge in the transition-wake region ( $${0.45}< x/W_A < 1.5$$ 0.45 < x / W A < 1.5 ), forming a combined wake in which the individual contributions are no longer apparent. In the far-wake regime ( $$x/W_A > 1.5$$ x / W A > 1.5 ), clusters’ wakes are akin to those developing downwind of a single isolated building. Accordingly, new local and global scaling parameters in the near- and far-wake regimes are introduced. The decay of the centreline velocity deficit is then modelled as a function of the three parameters considered in the experiment.