Chimneys and other slender structures with circular cross-sections are vulnerable to cross-wind excitation by fluctuating pressures due to vortex shedding. Regular vortex shedding from such structures is often strong enough to produce large dynamic forces in the cross-wind direction. If the damping of the chimney is low and the wind creates vortices that coincide with the natural frequency of the structure, high-amplitude vibrations will occur that could lead to fatigue damage and even collapse of the structure.
Wind tunnel section-model and aeroelastic-model tests can be used to provide appropriate aerodynamic data required for the design of tall chimneys. The wind tunnel can also be used to examine aerodynamic interference effects for pairs or groups of closely-spaced chimneys.