On the Relationship Between Added Mass and Added Damping

A surprising relationship exists between the amplitude and phase of a vibrating system. For an item vibrating in a fluid flow the phase of the fluid pressure (relative to the motion of the structure) can be deduced from the amplitude of the pressure. This strong dependence of the phase on the amplitude provides a means for checking the correctness of measured data and severely constrains the form that a mathematical model can take. The relationship between amplitude and phase is completely general and the paper gives various examples from theoretical models and experimental data. One interesting consequence of this relationship follows from the observation that phase angles only exist because of damping. Hence damping, due to the fluid, is linked to added mass.Copyright © 2002 by ASME