The aerodynamic admittance of two-dimensional rectangular section cylinders in smooth flow

A technique based on the generation of discrete-frequency cross-wind velocity fluctuations has been used to directly measure the aerodynamic admittance functions for a range of two-dimensional rectangular sections in smooth (low turbulence) flow. Results are presented which demonstrate that, for smooth flow, Sears' function increasingly underestimates the aerodynamic admittance of rectangular sections as the chord-to-thickness ratio of the section decreases. An empirical equation and a physical explanation for the results are advanced.