Fluid structure interaction analysis of flexible beams vibrating in a time-varying fluid domain

In this work, the transversal vibration of a submerged cantilever beam is studied with a time-varying fluid domain taken into consideration. The elastic beam is modeled using the Euler–Bernoulli beam theory, and the fluid is simplified by potential fluid theory. The governing equations of this fluid-structure interaction system are obtained using the mode superposition method and Galerkin’s method. Then the influence of the time-varying fluid is investigated in detail, based on modal analysis and transient analysis. Time-frequency analysis is given for signal processing of the obtained response, as the frequencies are time-varying. The analytical results obtained in this paper show good agreement with numerical results by ANSYS and results in the previous study. This study reports a new phenomenon that changing of the fluid induces an additional nonstructural damping, which is proportional to the velocity of the depth changing of the fluid. The induced damping influences vibration of the beam significantly and must be taken into account in dynamic analysis of structures in a time-varying fluid.