Abstract:
Wind flow over low-rise buildings is quite complicated because of the flow separation over the
roof. Accordingly, wind flow over roof-mounted objects such as water tanks, solar panel arrays,
solar water heaters, and chimneys mounted on a low-rise building can drastically influence the
flow patterns and pressure distribution on roofs and the object. A series of Computational Fluid
Dynamics (CFD) simulations were conducted to estimate the drag forces on objects and lift
forces on the roof. Different shapes of objects were modelled on the leeward and windward
slopes of a gable roof to estimate their susceptibility to wind damage. Wind-induced pressure
on roofs was estimated to investigate how these objects affect the wind flow over the gable
roof. This study gives suggestions for the selection of the best aerodynamic shape, orientation,
or installation location for a certain roof-mounted object to avoid wind damage. The lift
coefficients showed a variable change with different shapes of objects mounted on the
windward and leeward slopes of the roof. The results showed that the objects mounted on the
windward slope are more prone to wind damage as they experienced the largest wind loads,
and objects with sharp edges experience the highest drag forces. The solar panel array mounted
on the leeward slope closer to the ridge showed a 51% reduction in lift coefficients and the
solar panel array mounted in the middle of the windward slope showed a 42% increase in lift
coefficients compared to the bare roof case. Finally, this study recommends that it is safer to
mount objects on the leeward slope and mounting a solar panel array on the leeward slope
closer to the ridge can reduce the overall lift force acting on the roof of a low-rise gable roof
building. Also, this study recommends avoiding solar panel arrays installed at the middle of
the windward slope as it can compromise the safety of both the object and the roof.
