Attenuation of the unsteady loading on a high-rise building using feedback control

Abstract

The unsteady wind loading on high-rise buildings has the potential to influence strongly their structural performance in terms of serviceability, habitability and occupant comfort. This paper investigates numerically the flow structures around a canonical high-rise building immersed in an atmospheric boundary layer, using wall-resolved large eddy simulations. The switching between two vortex shedding modes is explored, and the influence of the atmospheric boundary layer on suppressing symmetric vortex shedding is identified. It is shown that the antisymmetric vortex shedding mode is prevalent in the near wake behind the building, with strong coherence between the periodic fluctuations of the building side force and the antisymmetric vortex shedding mode demonstrated. Two feedback control strategies, exploiting this idea, are designed to alleviate the aerodynamic side-force fluctuations, using pressure sensing on just a single building wall. The sensor response to synthetic jet actuation along the two ‘leading edges’ of the building is characterised using system identification. Both the designed linear controller and the least mean square adaptive controller attenuate successfully the side-force fluctuations when implemented in simulations. The linear controller exhibits a better performance, and its effect on the flow field is to delay the formation of dominant vortices and increase the extent of the recirculation region. Feedback control that requires a smaller sensing area is then explored, with a comparable control effect achieved in the attenuation of the unsteady loading. This study could motivate future attempts to understand and control the unsteady loading of a high-rise building exposed to oncoming wind variations.

Attenuation of the unsteady loading on a high-rise building using top-surface open-loop control

“…Thus four different oncoming wind angles with respect to the shorter cross-sectional side of the building (see figure 1 a ), , , and , were investigated numerically. When at , the flow set-up of simulation matched the unforced case of our previous work (Hu & Morgans 2022).

Figure 1.( a ) Top surface of the high-rise building; ( b ) flow set-up, showing the CAARC building model, ground, the atmospheric boundary layer and the computational domain.

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“…The synthetic eddy method, introduced by Jarrin et al (2006), was used to generate an inflow velocity profile with the 'target' mean flow and turbulent characteristics. This method shows a good performance in reproducing the prescribed turbulence characteristics and was well tested and validated in our previous study (Hu & Morgans 2022).…”

“…Thus four different oncoming wind angles with respect to the shorter cross-sectional side of the building (see figure 1a), α = 0 • , 10 • , 20 • and 45 • , were investigated numerically. When at α = 0 • , the flow set-up of simulation matched the unforced case of our previous work (Hu & Morgans 2022). shows the sketch of the computational domain used.…”

“…Based on the experimental data from Obasaju (1992), several numerical studies analysed aerodynamic forces of the building (Huang, Li & Wu 2010;Tominaga 2015;Yan & Li 2015;Ricci et al 2018;Thordal, Bennetsen & Koss 2019). Hu & Morgans (2022) numerically analysed the effect of accounting for the atmospheric boundary layer on the flow structures around a high-rise CAARC building. They captured the intermittent nature of the spanwise vortex shedding, analogous to the FWMC flow, and found that the presence of the atmospheric boundary layer enhanced the antisymmetric vortex shedding at the expense of the symmetric vortex shedding.…”

“…In terms of active control, steady jets near the spanwise leading edges of the building have been employed to mitigate the mean and dynamic aerodynamic forces (Menicovich et al 2014). Feedback control strategies were investigated by Hu & Morgans (2022) using actuation along the two leading edges of the building and sensing the antisymmetric pressure signal on the rear building surface. Their controllers alleviate the aerodynamic side-force fluctuations successfully.…”