Aerodynamic admittance functions of rectangular cylinders

This paper shows comparison between analysis and measurement of aerodynamic admittance functions for lift and pitching moment of bluff bodies. The authors have proposed a new method for estimating aerodynamic admittance function using flutter derivatives. In this paper, the estimation method was applied to rectangular cylinders with and without triangular fairing. The directly measured aerodynamic admittance functions were in good agreement with the identified ones using flutter derivatives. However, the obtained aerodynamic admittance functions had different tendency when compared to Sears’ function. It was obvious that the discrepancy between the obtained ones and Sears’ function was due to the different growing process of the transient aerodynamic forces (i.e., identified equivalent Wagner's functions). Comparison with Scanlan's formula was also discussed.