Drag or Along-Wind Response of Slender Structures

Theoretical approaches to the evaluation of the response of slender structures in turbulent shear flow have been proposed by a number of researchers. There are, however, limited experimental data supporting these developments and the assumptions upon which they have been based. In the present paper, the theory is reviewed briefly and the assumptions and necessary data examined in the light of recent experimental results. The theory is applied to predict the response of a slender tapered stack of circular cross section and the predictions compared with experimental observations of the behavior of a model stack in boundary layer flow. It is demonstrated that quasisteady approximations are adequate for wavelengths greater than about five to ten times the width of the structure and that the extension of the quasisteady approach to shorter wavelengths will, in general, yield a small overestimate of response. It is also shown that estimates of aerodynamic damping based on quasisteady assumptions are adequate.